Symptoms
I am using an APS package that provides upgrades using PBA APS (for example Windows Azure Pack aka WAP), upgrade order is placed and processed but no upgrade is triggered on application backend.
Cause
affects only PBA installations upgraded to PBA 5.5 from previous versions
Attributes are not applied to upgrade orders (UG), they are going to be deprecated in next PBA version
Resolution
Switch to change orders (CH), more on this here.