Hello,
1) I see that you logged out from the Cloudflare account https://prnt.sc/ujLX9TBAfhjS and we can’t clear the cache again. Please, log in to your CF account and don’t log out till we finish. Or better provide us with a login and pass to your Cloudflare account and we’ll be able to clear the cache by ourselves and also check the CF settings because something there could be the reason of the issue.
2) Could you clarify with your hosting provider if you don’t have any redirects or blocking of POST requests? Because we see that our custom requests disappear.
3) Could you, please, tell us who added this code to your wp-config file?
define( 'CONCATENATE_SCRIPTS', false );
Because it’s not the default code of the config file and we want to understand who and why added that.
Reards