Users may not able to able to see Help >Diagnostics option or get an error “Function Not Available to this Responsibility. Please check with your system administrator.”

These profiles need to be set at user level. So specific user can access this functionality (ex. Support folks/Developers)

Navigation: Go to System Administrator responsibility
Profile> System

Profile Option Name: Utilities:Diagnostics
User Level: Yes

Profile Option Name: Hide Diagnostics menu entry
User Level: NO

Save changes
Have user logout of Oracle Application and login again

User should be able to access Help >Diagnostics Menu