404 on URL/author/ page for individual member

I’ve searched the forum and found various 404 problems, but nothing as straightforward as “my author pages show 404”, so I’m posting. I’m sure it’s something simple.

Everything looks beautiful in my admin. Users (aka authors or members), fine.

The page generating the “members” list at URL/members/ is fine. Clicking on any member, however, returns 404 at URL/author/*whateverauthor/

Permalinks are set to URL/postname/

I have changed my path settings to include or not include www before domain name and it seems to make no difference; that only tosses me out of admin.

I’d appreciate any ideas, thanks.