@dunlix (and others)
Thanks, the disable plugins suggestion worked. Apparently it was the "sanitize html" plugging that was causing the problem.
Not even sure why we had that still installed.
Thanks all for the troubleshooting help!
I've never seen this error before in the admin panel:
You are running NodeBB v1.12.2.
Failed to look up latest available version of NodeBB
What might cause this?