Won't accept mp4/avi

[Firewallednonspeaker]

Trying to test out its editing features with something simple and I can't even import an MP4. MP3s are accepting just fine, but any video format I attempt too import states that an error must have occurred.
Can anyone help me with this? I'm kinda losing my mind at this video editor not being able to handle a video.

[bajecznie nawdychany]

MP4 is a container. You can load it into Vegas if codec used for audio and video is supported by Vegas. I just drag&drop an old mp4 file and it was recognized by Vegas. However when I dropped new file it was not recognized by Vegas.

As I remember I was able to overcome the issue sometimes. I was using mp4muxer to export audio and video as separate files (no encoding, just pulling the tracks) and then load video into Vegas.