When you try to create a configuration item for a mobile device in Microsoft System Center Configuration Manager current branch, you may encounter a System.InvalidOperationException error. This issue can occur if the user who is assigned a custom security role does not have the proper permissions for the Custom Configuration Setting role.
We published a new KB article that discusses this issue and you can get all the details as well as a resolution here:
J.C. Hornbeck, Solution Asset PM
Microsoft Enterprise Cloud Group