I have two students in my class that run into major issues with video export in Pro Tools in their projects. Everything is working inside Pro Tools, but once they export to video, the audio in the bounced video is drifting out of sync.
Lots of variables, lots of tests, but no real solution. WIP with a moving target. The fact that there are now gazillions of video codecs and Apple throwing in some curveballs regarding what is no longer supported, and Avid, trying to catch up with all that.
More fun than you like to get into.
