Following in case anybody has figured this out yet. We do not use conversions and this pops up randomly but cannot figure out what causes it. Our latest transaction was for a part that was in quantity of each. All quantities on the PO and those received are the same as well as the UOMs.
The transaction PUR-STK was created when the part was received and seconds later the ADJ-CST transaction occurred to zero out the cost on the part in inventory with the same Inventory Variance - Pack Slip reference others have mentioned. This part is and always was set-up as average cost on both the sites and main part maintenance tabs. Later that day the parts were shipped to the customer with transaction STK-CUS but at zero cost since the ADJ-CST record was created.
Any insight on this or new findings would be greatly appreciated!