Just to follow up on this - in case anyone else is is experiencing a similar glitch - after many hours of experimenting it looks like if you have a manager assigned to an all caw tag match the game will freeze. However, if you take the manager off, then put them back on (in the game participant select screen) , it seems to load just fine. Weird little workaround, which may not help in universe much, but there it is.
I would really love it if the game designers could make it so we can simply choose to import tag teams or choose to link our base set-up with our universe set-ups. With the slow loading screens it takes hours and hours to set up the entrances and victories for caw teams for universe mode and for the base game. Pretty silly that they're still separate. HUGE waste of gamer time.