As far as I know my system is up to date.
I do not know about policykit. I have selinux disabled now. It was permissive before.
Here is what I get when running it as non root:
[rog@Asrockfc Documents]$ /usr/local/bin/grub-customizer
The value for the SHELL variable was not found the /etc/shells file
This incident has been reported.
Do I need to uninstall 2.5 before installing your new version?