The bug is caused by a deprecated function.
The Python script mrq_stills.py that creates the sequences attempts to use the deprecated function “sequence.add_master_track(unreal.MovieSceneCameraCutTrack)”.
As a workaround, you can replace your engine installation path with the new function “sequence.add_track(unreal.MovieSceneCameraCutTrack)”: “UE_5.x/Engine/Plugins/MovieScene/MovieRenderPipeline/Content/Python/mrq_stills.py”