WordPress Customizer Keeps logging me out! Why? How to fix!?

WordPress Customizer Keeps logging me out! Why? How to fix!?

Whenever I go to use Customizer on my WP site, it keeps logging me out.

It was working fine last night. Actually, it was doing it to me before but then seemed to sort itself out somehow. But today on trying to use it again and customize my site. It keeps logging me out again!


I've tried searching around about this but virtually everything found suggest making sure the URLS in WordPress Address (URL) field and the Site Address (URL) field in Settings page are the same. Well they are! They always have been.

I've tried changing themes. The same thing happens.
I've tried disabling all pluigins. The same thing happens.

It just keeps incessantly logging me out and wont let me customize my site.

Has anyone else ever experienced this with WP and know the way to fix it?

Your help greatly appreciated.

Thanks!