I'm using the most up-to-date version of Audition, on a Mac with OS 10.14.6.
I'm importning .m4v video files into Audition's waveform editor, and am encountering an occasional but repeatable issue. When I import certain video files, the video preview will show up fine at the start of the timeline, but at a certain point the preview window will go black during playback. The point at which this happens is different depending on the videos - some will go black after 5 or 10 minutes, some after 60+ minutes, but even if I close/restart/reimport, the point at which one specific video shows black will be the same. Once this happens, if I stop/pause playback, the preview screen will then display the video at the current frame - but once I restart playbck, the preview goes black again.
I'm not doing anything intensive at the time - simply playing back and adding markers. The intent is to mark and pull samples from the videos, many of which are in foreign languages - so I need to be able to see the subtitles in the preview before marking a sample to export later. I've tried lowering the preview resolution, closing all other programs, etc. and nothing has worked. The videos play back with no problem in both VLC and QuickTime.
It sounds like you're hitting an arbitrary memory limit imposed by Audition. I have seen this happen, but assumed it was in error on my part (encoding or something). Audition is an audio editor that includes a single track video preview, so it's never going to be the best way to really see video (I know we all know that, but it's worth saying).
Also, the preview resolution may unload your GPU a bit, but the file still has to be read into memory. Have you noticed the larger files go black sooner than smaller ones? If there is a corrolation there I'd say you're hitting a read buffer in Audition. Have you tried reencoding the files? Maybe at lower resolution, just to see if it makes any difference?
One other thing to consider (really an addendum to the last thing): m4v is a wrapper format, similar to mp4 (but not identical). Premier doesn't like them very much, in my experience (but ultimately that comes down to the codec). If the files are not DRM protected, you may be able to get Audition to deal a bit better with them if you change the extension to .mp4 (source).
Even if this isn't the problem, you'll save yourself some headache using .mp4 instead of .m4v in the future. It is an ISO standard wrapper instead of Apple's version of it.
Hope this helped, but again Audition is not really built to handle video (though I'll say it reads formats Premier Pro won't).
Exactly the same with me with mp4 videos longer than 10 minutos. I always have to transcode in premier to avoid this issue. In my case i have to use audition due to proceed dubbing works
In my case i transcode to the same mp4 file with less resolution. so it works.
Should point out that under Edit>Preferences there's a page called Memory that will let you reallocate RAM. Whilst using Audition for video replay, I allocate 100% of it to Audition... Also, there are some other video settings in Edit>Preferences>Video that might make a difference.
I had a 43 minute project. In Au the video would go black at about 26 minutes in. So, back in Pr, I found a good place to cut the project about halfway through. Made two Pr timelines - one for 1st half, one for 2nd half. Both timelines work in Au - no blackouts. This is the only way I could get around this major pain in the ass. This is the first time I've run into this in 11 years. Looking at replies seems like it's happening more lately? Hope there's a fix soon!