I've added a couple of custom attributes to a resource. When I change them "manually" through the portal, I can change the values for these attributes without any problems. When I try to update these values using FIM PowerShell cmdlets it fails with "Operation is not valid due to the current state of the object.". If I run the same Powershell command to try and change a standard resource attribute (e.g. Description) it all works with no errors.
The MPR has the following settings:
Set of requestors: Administrators (user running the PS is in this as well)
Operations: all selected
Permissions: Grant permissions selected
Target Resource before/after: All Computers
Resource Attributes: All attributes