Reminders app on iMac not syncing

I tried the obvious thing, namely, I went into Recovery and reinstalled the OS. As I've noted elsewhere, this is a somewhat more involved process than it used to be. After like six restarts, my desktop came back. No change in Reminders, tho.

I use Reminders mostly on my iPad and iPhone, and it seems to be OK there. So, if I don't resolve it, I'll hope for MacOS 26; apparently there's a whole new Reminders, maybe it'll fix whatever's going on.

I'm still open to suggestions.

Thanks,

Jeff