No preview in managing themes

I used to have the older version of Custom Community.
After the update, my formatting changed.

Now, when I go into Manage Themes, I can’t generate a preview when I start to customize?

When I try to make a change anyways, and hit Save, nothing loads. The save button greys out and the page just never loads. The tab on my browser says “Customize: Loading…”, but even after 10 minutes, nothing is there.

The big problem though, is I now have no site: https://planetlew.com/ !!

Unless I pick a different theme. Then I can get most of my site back (just not the pages other than posts on the home page), but I prefer the Custom Community theme.