Hi Miguel,
Also I have one doubt that why you are picking in unit boxes and putting in unit pallets.
Any specific business need for this?
I suspect as you are picking 6 boxes and putting 5 pallets it could be the unit conversion making system still believe that the inventory for batch Z95 is still remaining while picking Z96.
I think if you pick 6 boxes and put 6 boxes you should not get this error.