Acrobat Pro DC Recent Files List Empty

I've been using Acrobat Pro DC (running on Windows 10) for about 2 weeks now... opened many files in it, but the File Lists / Recent screen shows nothing. (Previously, in Acrobat Pro XI, there was always a longish list.) If I look at the File menu, there are 5 recently opened items listed there, but if I click View All Recent Files... it goes back to the empty screen. Recent locations has data. The Documents settings show Documents in recently used list: set to 100.

I can't figure out what's wrong. Ideas?

Thanks,

Donna