first, I read the threads and documentation about changing IDs. I may have miss something, for sure, but I read before posting.
I created my SE network login with my gmail address some years ago. Now, I'm trying to change the email address I use to connect SE. I also read, I can't remove the first email account to create my SE logins, ok.
I ran the procedure to add new login, and save the data to be widespread on the whole SE network. This seems to work because if I connect any category and click Edit -> My logins, I see:
my new email address (with change password and remove actions)
But, I don't understand why I can't connect https://openid.stackexchange.com with my new credential, this leads to "No account found with this email address". Only the old address works.