MM 2024.2.2.3222: all non-WMV/AVI video fails to play after Windows 11 26H2 / KB5124010

[whudson]

Since early October, MediaMonkey will not play most video files on two separate PCs. Playback either does nothing or shows a black screen. On exit it sometimes throws “Window is not loaded yet” (SwitchWindow.updateContentBounds, controls/switchWindow line 115). Video had worked for years until then.
Setup
• MediaMonkey 2024.2.2.3222, freshly reinstalled, MM codec pack installed
• Windows 11 Pro 26H2, build 26300.9550 (KB5124010 and KB5121794 installed 30 Sep)
• PC 1: RTX 4090, current NVIDIA driver. PC 2 fails in exactly the same way.
What plays and what doesn’t (same files, both PCs)
• Fails: H.264 in MP4 (with AAC, with MP3, or silent), H.264 in MKV, MPEG-4 Part 2 in MP4
• Plays: WMV, AVI, AAC audio-only .m4a
• Legacy 32-bit Windows Media Player, MPC and VLC play every one of the failing files
Ruled out
• Files and network: local copies fail too
• Settings: fails with default settings (ini and persistent.json moved aside)
• Program files: clean reinstall, codec pack reinstalled
• Graphics driver: updated, no change
• 26H2 feature enablement: uninstalled KB5121794, no change
• Monitors: both monitors tested
Observation
While stuck on an MP4, MediaMonkeyEngine.exe had loaded f_MP4.dll, f_video.dll and Media Foundation (mf.dll, mfplat.dll, mfreadwrite.dll), but no video decoder of any kind. The process was still responsive.
I can supply small test clips and a memory dump of the stuck engine. Please let me know what logs you need.

[Lowlander]

Please capture this in a debug log (step 4b) and attach the log to a Support Ticket: viewtopic.php?t=86643

This will help a developer analyze why this doesn't work on your setup.

[Rob_S]

Just FYI, I had not noticed, because I usually use VLC player for videos but all my mp4 videos from my camera will no longer play in MM 2024 latest version, with the latest windows 11 update. I have not purchased a codec pack.

Before asking people to submit debug logs has anyone actually tried this using MM 2024 and Windows 11 26H2??

[whudson]

Thanks for that info Rob. I have tried with and without the MM Codec pack. It makes no difference.

[MiPi]

Tracked as: https://www.ventismedia.com/mantis/view.php?id=22408
The main reason is bug in the last Windows 11 update.