We defined SOP in months. However during SOP transfer to demand management, our independent requirements are

Check transaction OMPA for general split. OMPS - based on the MRP group. Ensure that MRP group assigned to the material. Delete any allocations in these tables. Then periods will be transferred to Demand Management with the same splits as in SOP. Also check whether the value of period is set as "month" at your plant level in Transaction 'OMP7'