SAP SuccessFactors Goal Management
This has been seen when clients use a field in the Milestone section named ‘category’.
As a goal plan will also have a default category field this can cause a conflict as you end up with "category" and "Category" resulting in the error Field Name : category Invalid Enum :
Note: Category field is required so system won’t let you save your goal plan if you delete it. To work around this issue remove it and the permissions associated with it via your XML.
KBA , LOD-SF-GM-ADM , Admin Tools, Settings, Permissions , Problem