Errors on MP4 export in Most Current Premiere Pro

We have the latest premiere pro on 3 of our imacs V 15.0.0 (Build 41).  When exporting .mp4 files  the last few frames or last couple seconds (depending on lenght of the video) will freeze up (image) and cut out sound.   

Example mp4 exported from Premiere (watch last few seconds and video will freeze)

https://vimeo.com/532076676/9dfc917919

Here's what the video should look like. Same video exported as .mov then uploaded to vimeo. Plays perfectly through the end.

https://vimeo.com/528170301/568345abcf

I've tried changing every setting withing MP4 export options (CBR, VBR, other presets etc.... )No fix.  However when I export in .MOV it works perfectly.  Tried exporting .mov, then adding it to media encoder to export to mp4, same issue.   Right now my only way to deliver an .mp4 to my clients, is export a quicktime, upload to vimeo, wait for them to do the conversion, then send the vimeo converted MP4 to my clients...... Very Very bad situation. This is happening on 2 imac pros and a 2020 imac all updated.  Never experienced this issue till V 15 was released. Anyone else seeing this issue? Adobe can you please help us trouble shoot/