As an update of my precedent message : the mentioned problem occurs when using the Divi frontend login form.
The login redirect works fine if I use the WordPress backend login form.
I’m having the same problem too on https://sectioninformatique.ch
The logout redirect does work fine, send user back to homepage.
But the login redirect parameter seems to have no effect. The user is always redirected to the WordPress backend. I tried to redirect to different site pages, including the homepage of my site but still no effect.