Need confirmation about Upgrade Promotion behavior

Hi All,
Customer is facing an issue with upgrade promotion and I would appreciate if you could confirm if they are facing a bug or expected behavior.

When upgrade promotion is done on an asset that has been disconnected, then reactivated, the line items of the CP under the promotion are all set to action code = ‘Add’.

Product/Promotion Setup:

MTS Promotion 1
MTS Root Product         Default cardinality = 1
 MTS Child Product 1     Default cardinality = 1

MTS Promotion 2
MTS Root Product         Default cardinality = 1
 MTS Child Product 2     Default cardinality = 1


Test Case:   

1-) Create an order, for a specified account, and add a promotion line that includes a CP bundle.