Cost variance and Deferred COGS

Hello,

For invenotry items which we ship, at the time of  ship confirm.

Current entry , inventory is getting credited and cost variance is getting debited and deferred cogs  has zero dollar entry.

Expected behaviour is that inventory should get  credited and deferred cogs should get debited at ship confirm.

Need to know what could be the reason for above to happen. We are in R12.1.3 and  there are no customization .

We are using FIFO costing.

Steps for shipping the item

Booking order, Pick release, Pick confirm, Ship confirm.

Appreciate any suggestion on the above.

Regards

Alex