Private relay Apple id remains locked even after updating my password

I've used a private relay apple id to log in to Goodnotes 6 App but got the password wrong when trying to log back in again. I got the message "This Apple ID has been locked for security reasons" so I reset my apple id which was fine for everything else Mac/iPhone wise and I now have a new password for my real email address which is my main apple id.

However when I try to sign in again to Goodnotes 6, in order to access the files I was working on, I have to still use the private relay address but apple doesn't recognise the new password and I still get "This Apple ID has been locked for security reasons" and tells me to reset my password. I'm just going round in circles. Its as if apple sees the private relay as a separate apple id or doesn't recognise the password change.

Can anyone help please?

In a nutshell - I've happily reset my apple id as requested (I tried 5 times and went round in circle) but it doesn't seem to associate the new password with the private relay one.#thanks