Hi @krascsenitsg,
For #1, could you enable Debugging on WordPress by enabling a plugin such as WP Debugging (or by manually adding these lines to your wp-config.php file), and revisit the Two-Step Verification page in the plugin again after doing so, to see if this results in any errors being logged in a debug.log file, located in the /wp-content/ folder?
Concerning #2, as you would normally de-activate Two-Step Authentication via the above section in the plugin, which you likely can’t currently access due to the described error message: you can follow the instructions in this article under “If the Administrator is locked out due to 2FA” to disable 2FA from the login page.
Kind regards, Jarno
