I was dealing with the same situation.
No issues installing latest TI version on Apache server as per documentation, was able to configure as per “getting started”, logged out from admin dashboard and could no longer log back in.
Then I remembered one of the steps in Apache configuration: https://tastyigniter.com/docs/master/installation#apache-configuration
In the .htaccess file I left RewriteBase / commented.
I removed the comment, saved the .htaccess file, after about a minute I tried to log back in, and it worked!
As a precaution to prevent any password “auto login corruption” that might create confusion when login in I updated my admin password. I tested with two browsers in regular, and private browsing, all good!
Hope this helps someone 🙂