Hello
The planning file will be only updated if there is a change on the material planning situation.
For example, if there is an inbound delivery, this is a planning element, which is relevant to MRP on a specific date. If you post the goods receipt on the planned date, there is no change on the planning situation and the planning file is not updated. If you post the goods receipt with a different quantity or on a different date, then the planning file should be updated.
BR
Caetano