Registration process does not work after update to Joomla 4

I'm making tests to migrate to Joomla 4. I've migrated the site to a testing domain.In the registration process I have 2 problems.

Problem 1: Ajax Username CheckerThe ajax checker does not find when a username is already in use (Probably not connecting with the database)Also when you input a username it opens a login tab below (Screenshot Attached) leaving the rest of the registration below.

Problem 2:Even if I turn off Ajax Checker. Once I fill up the registration form, when I click signup. It sends me back to the login page with a warning you must login first. (Screenshot Attached)

I've used the Tools to check out the Database, Sync users, plugins, etc, and everything checks out fine.

Any ideas, thanks! 

Joomla menu access permissions are causing an access denied state for CB. Check your Joomla menu items for CB to make sure they're set to Public. CB mandatory requires at least 1 public menu item to CBs profile page as it's the backup Itemid when a matching exact menu item isn't found.