Almost certainly some level of interference was the cause, as I have many BT devices active around me. Some TWS's also have had problems around me, but I've found enough that reject the interference well and are usable, and I needed the Amiron's to be as robust as I travel around into unknown "fields" of BT devices.
I had been ignoring it, hoping it wouldn't bother me, but it does enough that I needed to try to fix it and tried various devices to pair with and things would seem to be going along well and then it would happen again - just a brief drop out of audio - and most of the time it would recover. I think I only had to power off / on again a few times over the month or so I had them.
Amazon Prime let me extend the return period a couple of times, and in the end Amazon Prime returns now include a UPS pickup option - they come to your door with a shipping sticker - no printing required - and take it away to Amazon. I've got the Amiron Wireless and the DG60 boxed up ready and waiting at the door for tomorrow's pickup.
I'm half hoping Beyerdynamic comes out with a new wireless headphone in that price range with new BT hardware that is that much better that it will easily reject BT signals around me and be more reliable. The other half of me wants to order another Amiron Wireless headphone to see if it was just that unit that had the problem.
I'll spend time with other new headphones and IEM's for a while, and avoid thinking about it