diff --git a/includes/sanitizers/class-amp-tag-and-attribute-sanitizer.php b/includes/sanitizers/class-amp-tag-and-attribute-sanitizer.php
index ada07196abb..47b93f0803e 100644
--- a/includes/sanitizers/class-amp-tag-and-attribute-sanitizer.php
+++ b/includes/sanitizers/class-amp-tag-and-attribute-sanitizer.php
@@ -1850,7 +1850,7 @@ private function remove_disallowed_descendants( $node, $allowed_descendants ) {
 	}
 
 	/**
-	 * Loop through node's children and remove the ones that are not whitelisted.
+	 * Check whether the node validates the constraints for children.
 	 *
 	 * @param DOMNode $node Node.
 	 * @param array   $child_tags {
@@ -1878,24 +1878,22 @@ private function check_valid_children( $node, $child_tags ) {
 		}
 
 		// Verify that all of the child are among the set of allowed elements.
-		$removed_count = 0;
 		if ( isset( $child_tags['child_tag_name_oneof'] ) ) {
 			foreach ( $child_elements as $child_element ) {
 				if ( ! in_array( $child_element->nodeName, $child_tags['child_tag_name_oneof'], true ) ) {
-					$removed_count++;
-					$this->remove_invalid_child( $child_element );
+					return false;
 				}
 			}
 		}
 
 		// If there aren't the exact number of elements, then mark this $node as being invalid.
 		if ( isset( $child_tags['mandatory_num_child_tags'] ) ) {
-			return ( count( $child_elements ) - $removed_count ) === $child_tags['mandatory_num_child_tags'];
+			return count( $child_elements ) === $child_tags['mandatory_num_child_tags'];
 		}
 
 		// If there aren't enough elements, then mark this $node as being invalid.
 		if ( isset( $child_tags['mandatory_min_num_child_tags'] ) ) {
-			return ( count( $child_elements ) - $removed_count ) >= $child_tags['mandatory_min_num_child_tags'];
+			return count( $child_elements ) >= $child_tags['mandatory_min_num_child_tags'];
 		}
 
 		return true;
diff --git a/tests/php/test-tag-and-attribute-sanitizer.php b/tests/php/test-tag-and-attribute-sanitizer.php
index 04b12cce509..df6931b5cdb 100644
--- a/tests/php/test-tag-and-attribute-sanitizer.php
+++ b/tests/php/test-tag-and-attribute-sanitizer.php
@@ -72,17 +72,23 @@ public function get_body_data() {
 			],
 
 			'amp-animation'                                => [
-				'<amp-animation layout="nodisplay"><span>bad</span><script type="application/json">{}</script><strong>very bad</strong></amp-animation>',
 				'<amp-animation layout="nodisplay"><script type="application/json">{}</script></amp-animation>',
+				null,
 				[ 'amp-animation' ],
 			],
 
-			'amp-call-tracking'                            => [
-				'<amp-call-tracking config="https://example.com/calltracking.json"><b>bad</b>--and not great: <a href="tel:123456789">+1 (23) 456-789</a><i>more bad</i>not great</amp-call-tracking>',
-				'<amp-call-tracking config="https://example.com/calltracking.json">--and not great: <a href="tel:123456789">+1 (23) 456-789</a>not great</amp-call-tracking>',
+			'amp-call-tracking-ok'                         => [
+				'<amp-call-tracking config="https://example.com/calltracking.json"><a href="tel:123456789">+1 (23) 456-789</a></amp-call-tracking>',
+				null,
 				[ 'amp-call-tracking' ],
 			],
 
+			'amp-call-tracking-bad-children'               => [
+				'<amp-call-tracking config="https://example.com/calltracking.json"><b>bad</b>--and not great: <a href="tel:123456789">+1 (23) 456-789</a><i>more bad</i>not great</amp-call-tracking>',
+				'',
+				[],
+			],
+
 			'amp-call-tracking_blacklisted_config'         => [
 				'<amp-call-tracking config="__amp_source_origin"><a href="tel:123456789">+1 (23) 456-789</a></amp-call-tracking>',
 				'',
@@ -278,9 +284,7 @@ static function () {
 						'',
 						'
 						<amp-story standalone live-story-disabled supports-landscape title="My Story" publisher="The AMP Team" publisher-logo-src="https://example.com/logo/1x1.png" poster-portrait-src="https://example.com/my-story/poster/3x4.jpg" poster-square-src="https://example.com/my-story/poster/1x1.jpg" poster-landscape-src="https://example.com/my-story/poster/4x3.jpg" background-audio="my.mp3">
-							<i>bad</i>
 							<amp-story-page id="my-first-page">
-								<i>bad</i>
 								<amp-story-grid-layer template="fill">
 									<amp-img id="object1" animate-in="rotate-in-left" src="https://example.ampproject.org/helloworld/bg1.jpg" width="900" height="1600">
 									</amp-img>
@@ -295,9 +299,7 @@ static function () {
 								</amp-story-grid-layer>
 								<amp-pixel src="https://example.com/tracker/foo" layout="nodisplay"></amp-pixel>
 							</amp-story-page>
-							<i>bad</i>
 							<amp-story-page id="my-second-page">
-								<i>bad</i>
 								<amp-analytics config="https://example.com/analytics.account.config.json"></amp-analytics>
 								<amp-story-grid-layer template="thirds">
 									<amp-img grid-area="bottom-third" src="https://example.ampproject.org/helloworld/bg2.gif" width="900" height="1600">
@@ -325,9 +327,7 @@ static function () {
 									</amp-twitter>
 								</amp-story-page-attachment>
 							</amp-story-page>
-							<i>bad</i>
 							<amp-story-bookend src="bookendv1.json" layout="nodisplay"></amp-story-bookend>
-							<i>bad</i>
 							<amp-analytics id="75a1fdc3143c" type="googleanalytics"><script type="application/json">{"vars":{"account":"UA-XXXXXX-1"},"triggers":{"trackPageview":{"on":"visible","request":"pageview"}}}</script></amp-analytics>
 						</amp-story>
 						'
@@ -568,7 +568,6 @@ static function() {
 						'
 						<amp-accordion class="sample" disable-session-states="">
 							ok
-							<p>bad</p>
 							<section expanded>
 								<h4>Section 1</h4>
 								<p>Bunch of awesome content.</p>
@@ -585,8 +584,6 @@ static function() {
 								</figure>
 							</section>
 							ok
-							<div>bad</div>
-							ok
 						</amp-accordion>
 						'
 					);
@@ -735,7 +732,7 @@ static function() {
 			],
 
 			'remove_node_with_disallowed_ancestor_and_disallowed_child_nodes' => [
-				'<amp-sidebar><amp-app-banner>This node is not allowed here.</amp-app-banner><nav><i>bad</i><ul><li>Hello</li></ul><ol><li>Hello</li></ol><i>bad</i></nav><amp-app-banner>This node is not allowed here.</amp-app-banner></amp-sidebar>',
+				'<amp-sidebar><amp-app-banner>This node is not allowed here.</amp-app-banner><nav><ul><li>Hello</li></ul><ol><li>Hello</li></ol></nav><amp-app-banner>This node is not allowed here.</amp-app-banner></amp-sidebar>',
 				'<amp-sidebar><nav><ul><li>Hello</li></ul><ol><li>Hello</li></ol></nav></amp-sidebar>',
 				[ 'amp-sidebar' ],
 			],
@@ -790,6 +787,23 @@ static function() {
 				[ 'amp-sidebar' ],
 			],
 
+			'amp_sidebar_with_div_inside_nav'              => [
+				'
+				<amp-sidebar id="mobile-sidebar" layout="nodisplay" side="right">
+					<nav>
+						<ul>
+							<li><a href="https://example.com/"></a></li>
+						</ul>
+						<div class="some-div">
+							...
+						</div>
+					</nav>
+				</amp-sidebar>
+				',
+				null,
+				[ 'amp-sidebar' ],
+			],
+
 			'remove_node_without_mandatory_ancestor'       => [
 				'<div>All I have is this div, when all you want is a noscript tag.<audio>Sweet tunes</audio></div>',
 				'<div>All I have is this div, when all you want is a noscript tag.</div>',
@@ -1328,8 +1342,8 @@ static function() {
 			],
 
 			'amp-image-slider'                             => [
-				'<amp-image-slider layout="responsive" width="100" height="200"><span>Not allowed</span><amp-img src="/green-apple.jpg" alt="A green apple"></amp-img><i>forbidden</i><amp-img src="/red-apple.jpg" alt="A red apple"></amp-img><div first>This apple is green</div><strong>not allowed</strong><div second>This apple is red</div><i>not</i> <span>ok</span></amp-image-slider>',
 				'<amp-image-slider layout="responsive" width="100" height="200"><amp-img src="/green-apple.jpg" alt="A green apple"></amp-img><amp-img src="/red-apple.jpg" alt="A red apple"></amp-img><div first>This apple is green</div><div second>This apple is red</div></amp-image-slider>',
+				null,
 				[ 'amp-image-slider' ],
 			],
 
@@ -1339,6 +1353,12 @@ static function() {
 				[],
 			],
 
+			'amp-image-slider-more-bad-children'           => [
+				'<amp-image-slider layout="responsive" width="100" height="200"><span>Not allowed</span><amp-img src="/green-apple.jpg" alt="A green apple"></amp-img><i>forbidden</i><amp-img src="/red-apple.jpg" alt="A red apple"></amp-img><div first>This apple is green</div><strong>not allowed</strong><div second>This apple is red</div><i>not</i> <span>ok</span></amp-image-slider>',
+				'',
+				[],
+			],
+
 			'amp-fx-collection'                            => [
 				'<h1 amp-fx="parallax" data-parallax-factor="1.5">A title that moves faster than other content.</h1>',
 				null,