I have exactly this going on at the moment as well, its really curious, am on Nov 21 Beta
Customer said all was working well, Herelink battery got low so they put it on charge, and now its like Mavlink has stopped working. Have video and RC, but Solex/QGC/MP (on Herelink and Laptop with UDP) all see no telemetry.
As above, tried everything, have just reset the herelink and reinstalling it all as I type… came here to see if anyone else has seen it 