Login loop upon new installation

[UsernameIsNotAvailableIs]

Describe the bug
After doing a fresh installation and setting the "Admin" password, the login just loops back to the login page.

phpIPAM version
1.6 and 1.7

Your Environment (please supply the following information):

• phpIPAM version: 1.6 and 1.7
• OS FreeBSD 14.0
• PHP version 8.2.16
• Webserver Apache (2.4.58) behind HAproxy doing SSL offload
• Database MariaDB 10.11.7

Steps To Reproduce

Open the login page, login, get redirected back to login page.

Additional Info

After logging in both at the client and the server (Session Storage is files) 2 session files are created. One is empty, the other one contains "ipamusername|s:5:"Admin";ipamlanguage|s:11:"en_US.UTF-8";lastactive|i:1234567890;"
The string of the filename session files matches the Cookie ones in the browser (e.g. b6c2d6e8333e4c51e7df1c56498d5815)
Client side the empty session files matches the URL but only the domain part (e.g. ".mydomain.something") while the other matches the URL ("www.mydomain.something"). Example:

b6c2d6e8333e4c51e7df1c56498d5815 - empty file at server
d6d2e6f83234f4d51f7da1b56498c5815 - contains line from above

Both cookies have the same size (39 bytes in this example), both are HTTPonly, the second one additionally has the flags "Secure" and "SameSite" (the one with data in the session file server-side) while the other one not.
Server-side on config.php the samesite option has been set to "None".
It's a fresh installation so no plugins or other things have been configured / installed yet. The only difference is that the values from .htaccess (specially the rewrite part) have been migrated directly to the vHost configuration of Apache and "AllowOverride None" has been set.
Neither in Apache's error.log nor in PHP's log something is logged, even when enabling debugging. With version 1.7 the only logs are "PHP Warning: Undefined property: stdClass::$passkeys in /some_path/ip/functions/classes/class.User.php"