Audio has no level on some multicam nests

I'm using PP Version 23.1.0 (Build 86) on a 2021 MacBook Pro with M1 Pro, 16 mb ram, running OS Montery 12.5.

I'm working on a documentar with a timeline of about 100 minutes and I'm editing the interviews as multicams. It was working fine at first but then on certain clips the nested audio was silent on playback. I can still see the waveform of these clips on the timeline and they play normally in the source monitor.  My solution was just to replace the tracks without the nest. This works fine though it would be nice if I didn't have to replace all of my interviews.  But since on each export a few more audio clips stop working, it looks like I will have to go in and replace them all. Additionally, sometimes it's only one of the two or three audio tracks that becomes inaudible.  

I'm wondering if this is a known bug. I haven't been able to find anything on it.