I'm having strange issue with Blender 2.9 and above (so 3.0 too), which is not happening for earlier versions. Video Sequence Editor has trouble working with .mp4 encoded using PNG video codec, containing an alpha channel. It's rendered in Blender 2.81. VSE either imports it with correct number of frames but without alpha channel or just as a 1 frame with an alpha channel. Compositor in the same versions of Blender don't have this issue. Imports and interprets the alpha channel correctly. I'm working on Ubuntu 20.04.3 LTS GeForce GTX 1050 Ti and NVIDIA Driver Version:390.144. Installed Python versions: 2.7.18 and 3.8.10 Anything that comes to your mind will be helpful cause I have no clue where to start looking.