All bulk materials require quantity conversion; maintain item &

What causes this issue?

There is an item for the delivery that has not been fully processed. The
quantity conversion calculation has not been made. Hydrocarbon inventory
management materials require that all quantities for all units of
measure defined in the unit of measure group are calculated by the
Quantity Conversion Interface (QCI).

How to fix this error?

Process the item in question by making the quantity calculations. If
picking is required, the picking and the delivery quantity have to be
equal. If the picking and the delivery quantity is the same, the
quantity conversion calculation will be triggered automatically.

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.