Game always freezes at the mission screen

Unknown

I used to play this game a while back on this phone and just now started again. I've done the first few tutorial missions, but now it comes to this screen and none of the touch controls will respond. This used to happen occasionally before, but the game with snap out of it if I kept trying. LG G2, Android 5.0.2.

Unfortunately, I guess I can't attach a screenshot here...but anyway, it's the screen that comes up to select a mission for the Avengers tower.