I figured it was an adsense problem because I noticed that the customizer and elementor work just fine on pages where I don’t have any ad units.
@amit I have adsense, search console, and analytics code in my header that has been added using the Insert Headers and Footers plugin.
It seems like the problem is indeed adsense, because I’m able to customize posts without any ads. Is there a work around for this?
Cheers.