CentOS

I have created a directory on a CentOS 7.6 OS. I have provided this directory 777 (drwxrwxrwx) permissions recursively at the root level of the directory. The owner is root, the group is testers. I have added users to the testers group but all users added will get permissions denied when attempting to access them through either the terminal or GUI (Big X on folder). When logged in as root I indeed verify that 777 is applied to all files and folders within the directory.
I am also observing that I can not su to root from any user as well. Not sure if these could be related. I imagine there is something simple that I am missing but do not know what it is. Does anyone have any ideas on what I can do to try to and figure this out?

Sure you haven't gone and changed permissions across the whole tree?
What does ls -lh $(which su) give you?

Some time ago I had a problem with hidden characters
in some directory names. I checked it this way:
ls -1 | grep name-of-directory | od -Ad -tc