I experience this ..usually if T says something 'wrong' or I feel something I don't feel comfortable talking about. Or if there's something I really want to say but can't get he words out. I have yet to figure out how to bring it up, my T doesn't seem to be able to recognise when it's happening either.
Makes me feel extra lonely and like I'm not good enough and/or wasting my time there.

Sorry no advice, just wanted to let you know I experience it too.