Help with Link-OS-SDK - USB related features missing

Hello a little background information before I explain my issue. I'm developing around a new model of a Zebra printer for our application. We moved from the Zebra GK420 to the Zebra ZD420. The old application code built by a previous developer doesn't work as expected with the new printer despite the ZPL commands remaining the same.

I don't have access to the old developer's code so I can't troubleshoot any issues that arise from it. So I thought I'd try the SDK. But this is were things go wrong. The printer is setup to use a USB connection. When I downloaded the nuget package for Zebra the USB related classes weren't available for use.

So I searched around the discussion forums and downloaded the SDK manually. Then I added the necessary dll's to access the USB related classes. However, when actually using the classes in the application code. The projects don't compile. I'm at a loss for how to proceed.

Is there anyone else who has had a similar issue? Do the developers for Zebra realize that the dll/package may be broken?