Yes, I disabled uBlock Origin and I got the full YouTube experience, including plenty of ads. Based on advice I read on the uBlockOrigin site, I uninstalled the extension, and then re-installed it, and now things are working again. It may be that there was an update version that I was only able to get by re-installing, though that seems a bit clumsy.
Anyway, if this happens to anyone else using uBlock Origin, it seems to work to uninstall it and then re-install it from their site.