Session will not persists in CI 3.1.11 with CI Rest Api, no matter what I do

I cannot get my session to persist past the login.

I can see the session data in the sessions folder, the variables are saved. When a user logs in I am saving their user id and company id in the session.

But once I navigate to another page in my ReactJS project, and do another ajax call, the CI Rest API just returns unauthorized. The session token also changes.

I noticed this bug when I went from 3.1.10 to 3.1.11. But I am not honestly sure what is causing it and what to do.

I have spent 4 hours reading blogs and forums trying all the suggestions I could find and understand; nothing is resolving this.

$config['sess_driver'] = 'files';
$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 7200;
$config['sess_save_path'] = APPPATH . 'sessions';
$config['sess_match_ip'] = FALSE;
$config['sess_time_to_update'] = 300;
$config['sess_regenerate_destroy'] = FALSE;

$config['cookie_prefix']    = '';
$config['cookie_domain']    = '.localhost:4011';  // running dev project on my laptop
$config['cookie_path']      = '/';
$config['cookie_secure']    = FALSE;
$config['cookie_httponly']  = FALSE;

Yes I have sessions autoloaded.

This was all working and then it just stopped after 3.1.11.