Steps to reproduce:

• Create a Qt Quick application and use a UI element with an animation, e.g. BusyIndicator
  • Not sure whether any Qt Quick app will do - so far I only tested with Qt Quick Controls 2 and the Material style.
• Compile and run the Qt Quick application under e.g. Android (edit: it is also reproducible under Windows and some other platforms but it is not reproducible under e.g. KDE/Wayland)
• Wait until the animation gets stuck e.g. until the BusyIndicator no longer moves
• Produce some input events, e.g. click around the UI; this will temporarily let the animation continue until it gets stuck again soon

This is a regression in Qt 6.9.2. The previous patch release 6.9.1 works just fine.

Note that this is not just about BusyIndicator; the problem is also noticeable when pressing an ItemDelegate (at least when using the Material style where ItemDelegates are animated).

I first noticed the problem on an aarch64 Samsung device with Android 14 but was also able to reproduce it on an emulated x86_64 Pixel 8a device with Android 15.

I recompiled the very same application once more against Qt 6.9.1 and the problem was gone again. So I'm pretty sure the problem is caused by changes in Qt 6.9.2 and not by any changes my code.

I also added debug logging via QTimer so a log message is printed every second. This still works so the event loop is definitely not stuck. This is in-line with input events still being handled of course. So it is really only the Qt Quick animations which are stuck; not the app itself.

I have already tried to revert the commits 5ef73686cfb488dfc6a4077a2ecb12f883de1461 and 512d3f9a13b61e23d1554b39669a7464dce30b55 but the problem persisted. I can try reverting more commits and of course I can also try out possible fixes so I'd appreciate some input in that regard.

Note that I'm using my own build of Qt but I haven't changed the way I configure this build between Qt 6.9.1 and 6.9.2. I also use GNU/Linux as development host platform with both versions.

The animations also work just fine with Qt 6.9.2 when compiling for GNU/Linux and running the app under KDE/Wayland. So probably really only Android is affected by this.