Cannot update 'Household' field in Financial Services

This is working as designed.  The Household value is set by the Financial Services (formerly known as Financial Services Cloud) app when the following is true:

• The 'Primary Group' field on the Primary Owner's relationship with the Household is set to TRUE and 'Activities & Objects to Roll Up' field includes the object you are setting the household field on.
• 'Enable Group Record Rollups' field within the 'Wealth Application Config' custom setting was set to TRUE before setting the above.