Ultimate Member multisite login form issue

I originally had a single site in wordpress with UM plugin. The content is restricted to logged in users only, but for the homepage. When a user logs in and logs out, he/she is redirected to the homepage. When they click the homepage again to see restricted content, they are redirected to the login page. So far so good.

Then I created a multisite with the existing single site by editing the WP-Config.php and .htAccess files as directed on the kinsta.com blog about multisite setup for WordPress. I used the submaps for my new sites within the multisite setup (so not the subdomeins option).

Now when I follow the exact same process as described above within my already existing site but within a multisite environment, and try to login again after login out, I don’t get the login form anymore, instead I only see the profile page. After removing the history in my (Safari) browser, I am able to get the login form again.

I deleted all the cache (object and page cache), as far as I know. I de-activated and deleted the cache programs. I de-activated all other plugins . I tried all kind of changes in the settings of UM, But the issue persists. Only undoing the multisite setup and restoring the single site, made it work again as expected.

Any idea what might cause this?