It’s an .avi file as far as I know.
I’ve selected “Use timecode in file”. The timecode in file is: SMPTE Film Sync IVTC (23.976 fps, Video)
Format: Xvid MPEG-4 Codec
Attributes: 704x396x24, 00:00:01.293
Frame rate: 23.976 (IVTC Film)
Field order: None (progressive scan)
Pixel aspect ratio: 1.00000 (Square)
Alpha channel: None
I have also used “Gradent Map” on the file, but I tried masking on another file a while back with no effects on it and it acted up the same way.
Yes, I used to event pan/crop tool to mask.