Automatic substitutions/tactical changes on career mode

I've figured out what to do. Immediately after the half time whistle blows and the players start walking in, pause the game and jump in. When in the HT menu, don't switch back to tactical view. Instead, when you resume the game, wait for the kickoff to be taken (must be after the player kicks the ball). Now you can pause and go back into tactical view.

Annoying I agree, but it's the only way I've managed to bypass it.