Well, I spent an entire day only coming to this realization myself. I use mobaxterm with x11 forwarding so I can run pycharm and see video output from cameras and such. I had the same issue in addition to it magically setting volume to 0.
I really need x11 forwarding to work with mycroft. I see your solution was to just deactivate it, but have you successfully found something that would work otherwise?
I found if set it to automatically start on boot, it doesn’t get hung up on the x11 forwarding (makes sense). However, I’d like to not start it on boot…