For the longest time I couldn’t get back into global chat. It was just a blank gray screen. When I hit down on the dpad it never brought up the join channel option. When I went to guild chat it would bring up the join channel option, but it didn’t do anything.
The trick is, go to guild chat and press down to get to the join channel option but don’t hit A. Instead hit the bumper to go back to global chat with that button hilighted. It will carry the join channel button over to the global tab at which point you can rejoin global.