diff --git a/playwright/e2e/crypto/history-sharing.spec.ts b/playwright/e2e/crypto/history-sharing.spec.ts
index cdaa543bd97..ee275da84ac 100644
--- a/playwright/e2e/crypto/history-sharing.spec.ts
+++ b/playwright/e2e/crypto/history-sharing.spec.ts
@@ -56,4 +56,85 @@ test.describe("History sharing", function () {
             });
         },
     );
+
+    test("Messages sent when we believed the room history was unshared should not be visible", async ({
+        labsFlags,
+        browser,
+        page: alicePage,
+        user: aliceCredentials,
+        app: aliceElementApp,
+        homeserver,
+    }, testInfo) => {
+        test.setTimeout(60000);
+
+        // In this test:
+        //   1. Alice creates an encrypted room with Bob.
+        //   2. She sets the history visibility to "shared", but Bob doesn't receive the memo
+        //   3. Bob sends a message
+        //   4. Alice invites Charlie
+        //   5. Charlie can't see the message.
+
+        await aliceElementApp.client.bootstrapCrossSigning(aliceCredentials);
+        await createRoom(alicePage, "TestRoom", true);
+
+        // Register a second user, and open it in a second instance of the app
+        const bobCredentials = await homeserver.registerUser(`user_${testInfo.testId}_bob`, "password", "Bob");
+        const bobPage = await createNewInstance(browser, bobCredentials, {}, labsFlags);
+        const bobElementApp = new ElementAppPage(bobPage);
+        await bobElementApp.client.bootstrapCrossSigning(bobCredentials);
+
+        // ... and a third
+        const charlieCredentials = await homeserver.registerUser(
+            `user_${testInfo.testId}_charlie`,
+            "password",
+            "Charlie",
+        );
+        const charliePage = await createNewInstance(browser, charlieCredentials, {}, labsFlags);
+        const charlieElementApp = new ElementAppPage(charliePage);
+        await charlieElementApp.client.bootstrapCrossSigning(charlieCredentials);
+
+        // Alice invites Bob, and Bob accepts
+        const roomId = await aliceElementApp.getCurrentRoomIdFromUrl();
+        await aliceElementApp.inviteUserToCurrentRoom(bobCredentials.userId);
+        await bobPage.getByRole("option", { name: "TestRoom" }).click();
+        await bobPage.getByRole("button", { name: "Accept" }).click();
+
+        // Bob sends a message with "shared" visibility
+        await sendMessageInCurrentRoom(bobPage, "Message1: 'shared' visibility");
+        await expect(alicePage.getByText("Message1")).toBeVisible();
+
+        // Alice sets the history visibility to "joined"
+        await aliceElementApp.client.sendStateEvent(roomId, "m.room.history_visibility", {
+            history_visibility: "joined",
+        });
+        await expect(
+            bobPage.getByText(
+                "Alice made future room history visible to all room members, from the point they joined.",
+            ),
+        ).toBeVisible();
+
+        // Bob stops syncing, and sends a message with "joined" visibility.
+        // (Stopping syncing *before* sending the message means that the active sync will be flushed by sending the
+        // message, so that Alice's change to the history viz below won't be seen by Bob.)
+        await bobPage.route(`**/sync*`, (route) => route.fulfill({}));
+        await sendMessageInCurrentRoom(bobPage, "Message2: 'joined' visibility");
+        await expect(alicePage.getByText("Message2")).toBeVisible();
+
+        // Alice changes the history viz, but Bob doesn't receive the memo
+        await aliceElementApp.client.sendStateEvent(roomId, "m.room.history_visibility", {
+            history_visibility: "shared",
+        });
+        await sendMessageInCurrentRoom(bobPage, "Message3: 'shared' visibility, but Bob thinks it is still 'joined'");
+
+        // Alice now invites Charlie
+        await aliceElementApp.inviteUserToCurrentRoom(charlieCredentials.userId);
+        await charliePage.getByRole("option", { name: "TestRoom" }).click();
+        await charliePage.getByRole("button", { name: "Accept" }).click();
+
+        // Message1 should be visible
+        // Message2 should be invisible
+        // Message3 should be undecryptable
+        await expect(charliePage.getByText("Message1")).toBeVisible();
+        await expect(charliePage.getByText("You don't have access to this message")).toBeVisible();
+    });
 });
diff --git a/playwright/pages/ElementAppPage.ts b/playwright/pages/ElementAppPage.ts
index d7689230e1c..d53aec8081f 100644
--- a/playwright/pages/ElementAppPage.ts
+++ b/playwright/pages/ElementAppPage.ts
@@ -199,6 +199,21 @@ export class ElementAppPage {
         return this.page.locator(".mx_RightPanel");
     }
 
+    /**
+     * Opens the room info panel if it is not already open.
+     *
+     * TODO: fix this so that it works correctly if, say, the member list was open instead of the room info panel.
+     *
+     * @returns locator to the right panel
+     */
+    public async openRoomInfoPanel(): Promise<Locator> {
+        const locator = this.page.getByTestId("right-panel");
+        if (!(await locator.isVisible())) {
+            await this.page.getByRole("button", { name: "Room info" }).first().click();
+        }
+        return locator;
+    }
+
     /**
      * Opens/closes the memberlist panel
      * @returns locator to the memberlist panel
@@ -217,8 +232,8 @@ export class ElementAppPage {
      * @param userId - The user to invite to the room.
      */
     public async inviteUserToCurrentRoom(userId: string): Promise<void> {
-        await this.toggleRoomInfoPanel(); // TODO skip this if the room info panel is already open
-        await this.page.getByTestId("right-panel").getByRole("menuitem", { name: "Invite" }).click();
+        const rightPanel = await this.openRoomInfoPanel();
+        await rightPanel.getByRole("menuitem", { name: "Invite" }).click();
 
         const input = this.page.getByRole("dialog").getByTestId("invite-dialog-input");
         await input.fill(userId);