Hi There
We recently updated wordpress, our plugins and X theme at www.theflowfestival.com and are now getting this message when trying to access customizer, or cornerstone.
Session expired
Please log in again. The login page will open in a new window. After logging in you can close it and return to this page.
I have seen this topic posted elsewere and have tried deactivating the plug ins one by one, made sure everything is up to date, revalidated x theme, and have double checked that we are only on a direct server and not on wordpress.org so there is no connectivity issue there. Can someone from your team look into this?