Specifics, which I realize I left out:
I have tocP plugin installed. In this case, I had two instances, one right after the other, and I changed one to be the usual TOC process (class ="tc-table...") so that I could fix my old style TOC and change to the parent based one. "tocP" is a required class for the plugin, but "toc" is not for the core TOC. I forgot, and deleted the P to leave "toc tc-table-..." only I accidentally the P and the space.
And voila.
Now I'm keeping the numbered one.
So, if anyone wants to sort out how/why this works, it's probably somewhere in the tocP plugin...