Created attachment 185539 [details]
Screenshots of attempting to import videos, the error on render, and render window.

SUMMARY
As of flatpak commit 947d20d935101b6f5287133451417a177ca76c1a3439fb7bf0c0d509ecf7cf08, all video import and export fails.

Attempting to import a video (attempted both mp4 and webm) just imports audio, the video shows a transparent checkerboard. Dragging it into the timeline often crashes the program.

For rendering, the h264 export options are disabled with the message "Unsupported video codec: libx264," and other exports fail with the following message:

[libvpx @ 0x7fce300019c0] [IMGUTILS @ 0x7fce36e68a70] Picture size 0x1 is invalid [libvpx @ 0x7fce300019c0] [IMGUTILS @ 0x7fce36e68a40] Picture size 0x0 is invalid [libvpx @ 0x7fce300019c0] Invalid video pixel format: -1
[webm @ 0x7fce30000f40] dimensions not set [consumer avformat] Could not write header '/home/julian/Videos/untitled.webm'

STEPS TO REPRODUCE
1. Open KDE flatpak
2. Import any video, or import an image/audio and attempt to export to any format.

OBSERVED RESULT
The software fails or crashes.

EXPECTED RESULT
The software succeeds without crashing.

SOFTWARE/OS VERSIONS
Linux Mint, KDE Flatpak (25.08.1)

Occurs as of commit 947d20d935101b6f5287133451417a177ca76c1a3439fb7bf0c0d509ecf7cf08
Does not occur in commit 9f28077f3e213194be22abf099c44bd21d1c8f57c3b296ba8583690a333dd629 or earlier

ADDITIONAL INFORMATION
I have confirmed I have ffmpeg installed both through the system packages and flatpak:
System: 6.1.1-3ubuntu5
Flatpak: org.freedesktop.Platform.ffmpeg-full/x86_64/24.08