403 Error

Hello! After I set up User Sync I noted I couldn't go to the Customize area to change the WordPress site tagline. Instead, it gives me a 403 error. I'm completely sure if it was the plugin. When I deactivated everything and put it back to the basic WordPress theme it still has the 403 error. It is doing this on both my Superartist.market and Superartist.academy. I've granted access. Thanks for your help!