Is the item MRP/MPS planned ?
Please find below notes for reference.
The "in_source_plan" field is set to 1 (yes), when the item is "planned" in the source plan .
Otherwise it is Null or set to 2(no).
Source_plan here means supply schedule or demand schedule.
If a MRP plan is run which includes demands for MPS planned or MPS/MPP planned items, and the MRP is actually planning MPS items , then planned orders for the MPS item can be auto-released from MRP.
However, If MPS is passes as demand schedule to MRP plan, then MRP cannot create additional supplies for an item in the MPS.
This feature is internally controlled by looking at the item-org parameter "in_source_plan".
During the plan snapshot phase, all items to be planned in the plan are marked as "in_source_plan" = YES.This tells the netting engine whether to create new supplies and reschedules for the item. Since an MRP plan can plan for all items, "in_source_plan" will be yes for all items with demand in the plan.
Unless another plan (MPS) is fed as demand schedule or supply schedule to MRP , the in_source_plan is set to NO. This means MRP cannot plan them , even if additional demands are included for them.