diff --git a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
index 0f74ca40843b..5aab2e277693 100644
--- a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
+++ b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
@@ -3268,9 +3268,10 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
 
   /** The trace of comparison operations when performing `op` */
   def explained[T](op: ExplainingTypeComparer => T, header: String = "Subtype trace:", short: Boolean)(using Context): String =
-    val cmp = explainingTypeComparer(short)
-    inSubComparer(cmp)(op)
-    cmp.lastTrace(header)
+    explaining(cmp => { op(cmp); cmp.lastTrace(header) }, short)
+
+  def explaining[T](op: ExplainingTypeComparer => T, short: Boolean)(using Context): T =
+    inSubComparer(explainingTypeComparer(short))(op)
 
   def reduceMatchWith[T](op: MatchReducer => T)(using Context): T =
     inSubComparer(matchReducer)(op)
@@ -3440,6 +3441,9 @@ object TypeComparer {
   def explained[T](op: ExplainingTypeComparer => T, header: String = "Subtype trace:", short: Boolean = false)(using Context): String =
     comparing(_.explained(op, header, short))
 
+  def explaining[T](op: ExplainingTypeComparer => T, short: Boolean = false)(using Context): T =
+    comparing(_.explaining(op, short))
+
   def reduceMatchWith[T](op: MatchReducer => T)(using Context): T =
     comparing(_.reduceMatchWith(op))
 
@@ -3873,7 +3877,7 @@ class ExplainingTypeComparer(initctx: Context, short: Boolean) extends TypeCompa
   override def recur(tp1: Type, tp2: Type): Boolean =
     def moreInfo =
       if Config.verboseExplainSubtype || ctx.settings.verbose.value
-      then s" ${tp1.getClass} ${tp2.getClass}"
+      then s" ${tp1.className} ${tp2.className}"
       else ""
     val approx = approxState
     def approxStr = if short then "" else approx.show
diff --git a/compiler/src/dotty/tools/dotc/core/TypeOps.scala b/compiler/src/dotty/tools/dotc/core/TypeOps.scala
index 8089735bdb0f..0d8801b646ee 100644
--- a/compiler/src/dotty/tools/dotc/core/TypeOps.scala
+++ b/compiler/src/dotty/tools/dotc/core/TypeOps.scala
@@ -691,11 +691,22 @@ object TypeOps:
       val hiBound = instantiate(bounds.hi, skolemizedArgTypes)
       val loBound = instantiate(bounds.lo, skolemizedArgTypes)
 
-      def check(using Context) = {
-        if (!(lo <:< hiBound)) violations += ((arg, "upper", hiBound))
-        if (!(loBound <:< hi)) violations += ((arg, "lower", loBound))
+      def check(tp1: Type, tp2: Type, which: String, bound: Type)(using Context) = {
+        val isSub = TypeComparer.explaining { cmp =>
+          val isSub = cmp.isSubType(tp1, tp2)
+          if !isSub then
+            if !ctx.typerState.constraint.domainLambdas.isEmpty then
+              typr.println(i"${ctx.typerState.constraint}")
+            if !ctx.gadt.symbols.isEmpty then
+              typr.println(i"${ctx.gadt}")
+            typr.println(cmp.lastTrace(i"checkOverlapsBounds($lo, $hi, $arg, $bounds)($which)"))
+            //trace.dumpStack()
+          isSub
+        }//(using ctx.fresh.setSetting(ctx.settings.verbose, true)) // uncomment to enable moreInfo in ExplainingTypeComparer recur
+        if !isSub then violations += ((arg, which, bound))
       }
-      check(using checkCtx)
+      check(lo, hiBound, "upper", hiBound)(using checkCtx)
+      check(loBound, hi, "lower", loBound)(using checkCtx)
     }
 
     def loop(args: List[Tree], boundss: List[TypeBounds]): Unit = args match
diff --git a/compiler/src/dotty/tools/dotc/reporting/trace.scala b/compiler/src/dotty/tools/dotc/reporting/trace.scala
index fbbc3d990969..732e779e9bf7 100644
--- a/compiler/src/dotty/tools/dotc/reporting/trace.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/trace.scala
@@ -27,6 +27,18 @@ object trace extends TraceSyntax:
   object log extends TraceSyntax:
     inline def isEnabled: true = true
     protected val isForced = false
+
+  def dumpStack(limit: Int = -1): Unit = {
+    val out = Console.out
+    val exc = new Exception("Dump Stack")
+    var stack = exc.getStackTrace
+      .filter(e => !e.getClassName.startsWith("dotty.tools.dotc.reporting.TraceSyntax"))
+      .filter(e => !e.getClassName.startsWith("dotty.tools.dotc.reporting.trace"))
+    if limit >= 0 then
+      stack = stack.take(limit)
+    exc.setStackTrace(stack)
+    exc.printStackTrace(out)
+  }
 end trace
 
 /** This module is carefully optimized to give zero overhead if Config.tracingEnabled