MovieStim3 issue

OS (e.g. Win10): Win10
PsychoPy version (e.g. 1.84.x): v2020.2.3 (but also newest as of 5.1.2021)
Standard Standalone? (y/n) If not then what?: y
What are you trying to achieve?: non-glitching video presentation. Videos are under 10 seconds long. Often (but not always) video glitches and part of the video is missed. Misses a critical part of the video. Often at the end, but not always. I have multiple videos, its never consistent with which video glitches.

What did you try to make it work?: changed formats (both .mp4, avi, no difference). encoded with different settings (currently using those recommended in other threads, no difference) encoded video/audio in different sizes, different frame rate (no difference). Made presentation size smaller (did make it a little better but not perfect). Tried multiple computers (no difference), same issue on most powerful testing computer. Presented videos with a pause before and after (no difference).

What specifically went wrong when you tried that?:
No error message, and i am out of ideas and have exhausted ideas that I can find in forums.

Thanks for your help!