In the Editor, the last character or two are cut off at the right, as if the right margin were set to be negative. This is on a 15" 2015 MBP. (I haven’t downloaded Catalina on my Mac Mini as yet.)
I don’t have fixed-width or page view turned on, and I have Editor Right/Left margins set to 20 pts in Preferences->Appearance->Options. When I increase that to 50 pts or so, I begin to see all the text, but then I have ridiculous left and right margins.
UPDATE 1: I hid and unhid the Binder, and the Editor seems to be cured … but I can’t see all of the Inspector.
UPDATE 2: Closing and reopening Scrivener appears to fix the Inspector now. Reopening didn’t solve it BEFORE my previous experiments. Now it does. For now, at least.
UPDATE 3: I closed Scrivener again, reopened, hid the Binder and Inspector … and there’s a huge blank space on the right, where the Inspector would be. None of these problems occur on the Mac Mini, where I still run Mojave.
UPDATE 4: Close and reopen AGAIN seems to fix everything. Maybe.