Since last week, a large amount of items planned by MRP is not considering the item order lead time which leads to all these items having the same order and planned delivery date in the planned orders. Another thing that I have observed is that the Net Change flag for these affected items will remain as "YES" even immediately after the MRP run. I am clueless, any help will be much appreciated.

Are there also exception messages generated for these items?
Usually this issue happens when MRP cannot not plan the correct dates for the orders.
A problem in the planning could be an incorrect calendar setup.

Hi sdvries,

You are right, the problem seems to be the company calendar. I tried to do a manual update of the order date for a Planned MRP Purchase Order that has incorrect dates and got the error "Actual Calendar not found.........".

I am on Company Calendar Type "By Company" and I have checked and confirmed that our Company Calendar has been updated all the way to week 52 of year 2012 for Work Center ZZZ.

I have no clue where goes wrong.