I had the same issue. Typing into a book or the chat sometimes fixed it, although it also sometimes didn't let me type in those either.
I have noticed this issue as well. I've seen this same bug pop up in at least one previous version. It's unfortunate that this bug has returned.
This happens for me too. For me, it opens the touch keyboard specifically and I’ve been able to temporarily fix the problem by clicking on the chatbox with my mouse before typing.