looks like I got over the first part of the problem.
I had dabbled with a PWA plugin and chrome had stored local data and tried to access the service worker – which was gone after I had deactivated the PWA plugin.. So I had to manually delete the local cache and unregister the service worker for my site in the Chrome Developer Tools in the Application tab.
Now I am still stuck with this error when trying to save my site in customizer:
You need a higher level of permission.
Sorry, you are not allowed to customise this site.
And I am getting a 403 for admin-ajax.php