Threaded view issues, things missing
Seems to be working now after I ran the debug...
Any idea why it happened in the first place and how to fix?
Yes, I also see a js error on the console. This kind of issues is usually caused by either a conflict with your theme or with other plugins. So please try to find the problem maker one by deactivating the plugins one by one.
There are some excellent maintenance plugins for Wordpress. Install one and just enable Maintenance for a few minutes. And do all your tests.
I'm sorry but if you do not pinpoint your error (from where exactly it comes from), you will never be able to get proper help.