I had a issue where I went to attack a titan and at the EDIT TEAM screen right before you hit FIGHT the screen was pretty much blank besides the FIGHT button. No ability to see team or edit team.
I had already attacked so I had my team set and I hit fight and it lead to the fight ok. I had another flag and it did the same thing, blank screen.
I then went to farm and got the same blank screen at the EDIT TEAM screen.
I decided to log out and log in and it resumed with a correct EDIT TEAM screen fixing the problem, but it did happen, hope it doesn’t happen again.