We have recently update all machines to Encoder 15, as well as updating premiere and all Macs to Big sur. And we are having alot of problems rendering mp4 H264.
At the moment we recording many webinar/meeting and editing for our clients. Since the update the H264 render are loosing lip sync and the only work around is to render out quicktime, prores lt ususally, which keeps sync and then rendering the quicktime mov, in other (none adobe) software, to mp H264. This is massively time consuming.