Hi Patrik,
I am confused, unchecking this setting “UsersWP->General->Login->Redirect wp-login.php” was a solution for this issue since I started this thread?
In any case, I think that the issue is only partially solved.
Once logged in via the WP login page, it is not possible to close the session and log in again via the UsersWP login page without clearing the browser cookies before, since otherwise the redirect error shows. It is possible to log in again, but only via the WP login page. Therefore the redirect issue caused by the Jetpack cookie persists, and I understand that any user should be able to login via UsersWP login page, which is the login page that, as the site owner, I set as the default login page, as well as via the WP Admin page if the user is also a Jetpack user. Am I right? Do you plan to solve this issue sometime soon?
I look forward to your reply.
Thank you very much once again for your help.
Best regards.