Not sure who else has this problem, but for a while I would see the welcome screen after logging in, followed by a home page without the extra menu options - i.e. the script still didn't recognize me.
Cleaning out my cookies only helped temporarily.
I think I found the reason. I have other scripts elsewhere on my website that also use cookies. For reasons that are still unclear, some interaction must be in play that confuses the script.
Anyway in the admin config menu, I went to Cookie Settings, Cookie path, and changed it from blank to "/gallery" (the subdirectory I use) and I haven't had a problem since.
Posting this in case this helps others...