With 13.1 beta, I had to search to re-display my menu bar, which is a click on the AlittleA (Äa) button (Ipad), or on the phone, click the filename (on top), and then the Aa button and go through setting up the display. Or something like that, just like a first time setup. All came back for me.
Then, I crashed out completely on beta 13.2 this morning. Anohter problem entirely.