process order api is not honoring the Default Behavior for Subscription Item on Order Line set up as

Did set up the OM system parameter for Default Behavior for Subscription Item on Order Line as Subscription Service Line to default the 'Service' item type for the subscription item on the sales order line.

It works fine when the order is created manually in Order Management. But when I am trying to use process order api, then this set up is ignored and the order line is created as 'Standard Item'.

Due to the processing constraint, once the subscription line is created and committed on the order line through api, no change can be done.

Any idea?

Thanks