Bug - Audio intermittently muted until solo button activated and deactivated
Some audio tracks will intermittently stop playing back, however if you solo and unsolo a track (any audio track will do), the audio starts playing back as normal.
This started as of 12.1, and continues.
Steps to reproduce:
- Some audio stops playing back.
- Solo an audio track.
- Unsolo that audio track.
- Sound plays back as expected.

The issue could occur when an audio track was muted in a sequence and then the v12.1.1 project was saved and closed. When you reopened the project, the UI for the sequence no longer showed the audio track as being muted as the UI reset the toggle to show it as on. When a user would play back the sequence , not all of the audio tracks would appear to play causing them to possibly think it was a caching issue or codec related issue. Premiere was actually playing the sequence back correctly as those tracks were muted from the previous save state but the UI bug caused the issue where there was no indication that the track was muted.
Solution: (the Fix)
Once a v12.1.1 project shows this UI behavior it needs to be corrected and resaved. Note v12.1.2 will not correct this issue simply by opening the project in V12.1.2 .
You need to follow these steps to repair the project.
1. Toggle the Solo button on/off and the Audio track will correct the playback state. To keep it simple, Solo/Unsolo each audio track.
2. Playback the Sequence to insure that all audio tracks can be heard and monitored.
3. Save the Project
4. Quit Premiere Pro
5. Relaunch and issue should now be fixed.
As stated, the fix for this issue is included in the recent update, v12.1.2. This update keeps the UI bug from occurring so the user should not run into the issue again.