Transfer Order - lines split into Staged and Interfaced - why?

Summary:

Transfer Order - lines split into Staged and Interfaced - why?

Content (please ensure you mask any confidential information):

Hi - we are experiencing issues as demonstrated by this example Transfer Order.

When looking at the T/O on the Manage Shipment Lines screen, half of the ordered QTY of 24 has a Line Status of "Interfaced" while the other half is "Staged":

What diagnostic steps can I take to find out what is causing this type of issue, and how can it be resolved?

Thanks

Version (include the version you are using, if applicable):

26B