Cleaning out Block List "hangs" my iPad

Platform, device version and operating system:
iPad 6, iOS 12.latest

What you were expecting to happen, and what actually happened:
I decided to clean out my Block List in chat, assuming most spammers I’d blocked were no longer around. So I removed all but one name from my Block List – at least two of those names looked more like Discord names than GoW names. And then things got weird.

What I could do: change to any other tab in chat (green tabs on the left), scroll within those tabs, click on a player in Chat and see the Honour-assignment window.
What I could not do: close the chat window (to return to the game), activate Lite Chat (or probably any of the other buttons on the Chat Settings tab), post to Chat, view any player’s profile from their Honour-assignment window (I think the window just disappeared).
What I didn’t check (or don’t remember, because I was half asleep): some of the buttons, change portrait/title, see new message (I think I could, but I can’t recall).

I ended up having to force-close GoW and restart.

How often does this happen? When did it begin happening?
Only time I’ve seen it. I removed about 8 Players.