This was unexpected, and not documented at all in the SharePoint SDK.
When you create a UserMulti column, you must also specify Mult=”TRUE”, otherwise it will fall back to a standard (single select) User column type.
One thought to “Using UserMulti field in the CAML schema”
THANKS GOD!!!!! I was having HEADACHE searching WHY my field was always always like a User type colum even with the “UserMulti”