Inventory Reconciliation - Ending Quantity Higher

Hi,
We have been selling on Amazon for around 12 months, we ship quite bulky items with the FBA program, and so we get a lot of missing / damaged / defective items
I have recently run the ‘inventory reconciliation report’ on there for the whole time we have been using amazon.
For 1 particular SKU we have the below:
Beginning units - 0
Total units in - 9734
Total units out - 8788
Ending Quantity - 997

However, when we go to our available stock on FBA, we only have:
Available - 208
Reserved - 188

This is a difference of 601 units that we are supposed to have on stock, but we don’t
How are we supposed to approach this with amazon

Thanks for the help!!!