@theducks, Thanks for showing me where to look
It shows up under Scanners and Cameras on mine, see attached.
Poking around a bit also shows me that not all the files/directories are visible. My added SD card has an ebooks directory, only 7 of the 30 epubs I know are on there are displayed.
This seems consistent with what's been said in the last few posts.
It's official, I'm a "lost cause"
It's not a problem for me, I'll continue doing what I've been doing, but if you want me to test anything on my geriatric system, feel free to ask.