I make a Concentric mate with the heads-up menu. The parts snap together the way you expect.
I drag one of the parts to rotate it slightly.
I get another mate pop-up. This time the mate pop-up has a "lock rotation" option.
I click off to the side to get rid of the pop-up... because, I think to myself I already made a Mate, don't need another one. Then the original Mate then deletes itself.
What is going on? Is this a 'feature' that I am triggering without knowing it?