I'm aware of the mic-problems on some of the XM3s, and I had mine replaced. With my first pair, no one could ever hear what I said. After picking up my new XM3s, the first thing I did was to call a friend. "Yes, now it's good, I can hear you clearly now" was the feedback I got.  But then, I tried a couple of calls more, and experienced trouble again. This is my current situation:

If I do a factory reset on my XM3s, then re-pair them to my Samsung S8, I can make a call to someone with good quality. We can hear each other clearly, as it should be.

If I try to call someone after that, like half an hour later, or answer an incoming call, I can still hear the person clearly, but the person tells me I sound VERY distant. Like I'm in another room. I have to remove the headset and talk through the phone instead.  

Have anyone else experienced similar issues?

Firmware 2.0.0
Production month: 11/2018