Admin/Customize/Themes permanently loading

I installed Discourse yesterday. It’s fully updated and I didn’t install any plugins.

When I go to Admin/Customize/Themes I see the loader permanently spinning. I tried to just wait until it loads, but it stays like this for hours.

This is what console throws me:

Thank you in advance.

Just in case it helps someone:

I’ve just discovered this problem doesn’t happen when I access through Incognito mode.

Anyways, it would be nice to discover why it happens.

If it doesn’t happen in incognito mode, it’s most likely an extension installed in your browser causing the issue.

Most likely would be an ad blocker if you have one installed.