Sometime cost is posted against 601 movement type and sometimes not.

[saurabh_srivastava14]

Hi Team, 

We have scenario where we create sales order then a delivery and GI is done against delivery.
meanwhile this item is produced via Production order and after 101 ( keeping it in own unrestricted stocK) we do goods issue to customer with 601 movement type. 

but weird part is sometimes it is having value as 0 and sometimes it has some value . Can someone help what is driving this value at the time of GI against delivery ?
Attached screenshot with 2 case. where material 1 and material 2 are exactly same in terms of master data ( same material type, same valuation class etc.) for one case we have some value while for other case its 0. 

Any clue to investigate in particular direction will be helpful. Thanks.

-BR 
Saurabh