I've owned a couple of these the motorola and the AAwireless variety. In both cases, there are sometimes random glitches that occur - android auto failing to launch, etc. In all cases correcting the random error is resolved with a restart of the device (sometimes both phone and dongle).
Android auto has been going through multiple revisions of late, and my aawireless devices have been updated too. I have had no luck pinpointing where the actual cause of these issues originates. There have been too many variables to narrow things down before another change comes.
My sense is that for now - some degree of this glitchy behavior is going to be there for the time being. It generally works for me more than 90 percent of the time.