LOST UNITS DURING FC TRANSFER

We are experiencing problem RELATED WITH LOST UNITS WHEN FC TRANSFER HAPPENS. Amazon receives all the boxes with accurate weight and sign for it.

Then the Parent Primary FC receives all units. But when units move to other secondary FC, we see Negative units at that FC. Which end up causing discrepancy for our closed shipments and we have to contest the case.

APPRECIATE IF YOU PLEASE EXPLAIN THE PROCESS, REASON FOR THIS HAPPENING WHERE SOME OF THE FCS ARE EXTRACTING, REMOVING OR WHATEVER THEY ARE DOING WHICH CAUSED NEGATIVE UNITS. THESE NEGATIVE UNITS WHEN ADDED BACK TO FULLY RECEIVED UNITS, CAUSING DISCREPANCY OF LOST UNITS FOR US.

NEED TO UNDERSTAND THE AMAZON PROCESS BEHIND IT, PLEASE EXPLAIN