Customer is trying to set permissions using the File Manager via CCP > Hosted Domains > domain.tld > File Manager > domain.tld directory > Get Info, and they are not saved. Customer is trying to Add Write access to Anonymous Users. When you check the box and click save and go back in the box is no longer checked.
POA-91958 WebFileManager (Win) - After revoking of "Write" permission from anonymous users on PHP file via File Manager PHP script requires authentication
The issue has been fixed in OA 6.0 update 7. To workaround the issue on earlier versions of OA please contact Odin Technical Support.