UHD H264 export is corrupted and shorter than the rendered timeline

UHD H264 renders from Premiere Pro and Media Encoder aren't wrapping properly when they get to 100% and result in corrupt files.

Software versions:

• Premiere Pro Build 56
• Media Encoder Build 51
• Windows 11 Home 22H2, OS build 22621.1848
  
  

Steps to reproduce:

1. Edit a 24-minute timeline in UHD, using proxies.
2. Export to a UHD H.264 file.

OR

1. Edit a 24-minute timeline in UHD, using proxies.
2. Export to a UHD Prores 422 file (works fine)
3. Then import that file and add a new audio track and export as H.264 (fails)
   
   

Expected result:

A UHD H.264 file that will play back in full.

Actual result:

The media encodes to 100%, and the preview shows that it's getting to the end, but then it hangs for a long time at 100% and fails to wrap the file properly. The result is a UHD H.264 file that will play only part of the way through and then won't play anymore after an arbitrary point. The file cannot be imported into Premiere or into Media Encoder without causing the programs to hang indefinitely.

But, rendering to HD H264 files works perfectly every time.

Other attempts and results:

I also tried rendering to UHD ProRes 422. This worked perfectly.

I then tried re-encoding that ProRes file to H.264. This only worked once: when re-encoding the ProRes file on its own in Media Encoder. But when I needed to add alternative audio to the ProRes render in a separate Premiere sequence and export it from there, I had exactly the same problem as before. The render got to 100%, then failed to wrap properly, and I had a corrupted H.264 file.