Functions can be greyed out or not working because they are not applicable to the currently selected object.
For example, you may not have the correct object selected so functions will be unavailable. Also certain functions are only applicable to Standard CC characters so if you have a Non-Standard character selected then some functionality will be greyed out.
Please try to explain what you are doing when the problems occur and also let us know which functionality is unavailable.
Peter
Forum Administrator
www.reallusion.com