In the architecture manual the instruction MOVHI is listed in the index. It is intended to put an immediate value in the high part of the destination register.
But there's another "MOVHI" instruction: move value to register if condition is true, and if the condition to test is "HI" (higher), the syntax is the same as for the other instruction.
When simulating in IAR EW it is the second operation that occur. So the question is, what would the syntax be if you want to move an immediate to the high part of the register??