Login/Registration problems with WP Fastest Pro Plugin

Hi,

I have used WP Fasted plugin. And recently I also bought WP Fasted Pro. However, as my site was not launched, I was not carefully aware of various problems occurred due to some compatibility issue with WP Fasted plugin. Recently, my site was officially launched with my clients. However, there are various problems specially related with login. And currently, I have temporary deactivated WP Fasted and Fasted Pro plugins.

Some examples of the problems are as follows:
For instance, even though a user logged in, nothing has been changed on home page. However, other pages show the logged-in user icon as normal while the home page shows no logged-in user on the user icon. Only that home page shows no user logged in but other pages are ok. Secondly, if an user enters wrong user name and/or password, it presents several problems varied depending on PC, tablet and mobile. The first time that the user put wrong user name/or password, the website shows nothing changed. And then if the user puts the right user name and/or password, the website displays wrong user name and/or password message, which is weal. There are many various different problems occurred related with WP Fastest plugin. However, if I deactivate WP Fastest and its pro plugins, no any problems occur related with login/registration, etc. And then, I followed the guide give by WP Fastest plugin with disabling logged-in user for cache and no login page URL has been changed. But it still has various login/registration problems occurred.