Promotional Goods Modifier does not recognize line quantity changes after booking

Have a Promotional Goods modifier for buy 1 get 1 free.  After Booking the order, if a quantity change is made to the Buy item line, the Get Item quantity remains at quantity 1.
For example:
Enter Line 1 with quantity 1
Get item applied with quantity 1
Book order

Increase quantity on Line 1 to 6
Save
Get item applied with quantity 1.
It does not recognize the quantity change.

Thanks
Judy