Customizer not working after importing Highend theme

I recently purchased the highend theme and it worked for less than a day. Went to work on it the next morning and my customizer page only shows the tabs on the left, no site preview.

The tab for the customizer says “Customizer Loading”

I’ve tried disabling plugins, tried to use a default theme (it didn’t work anymore either).

I made the suggested edits to the wp-config.php file for increasing php memory (?)

Nothing has worked. Other browsers don’t work either.

Can’t edit anything.