Hi RickBoyett,
maybe you have installed the wrong agent.
My understanding is that the Server in the licensing is referred to a use case where you intend to deploy Windows Server OS for VDI. (to avoid Microsoft VDA for example)
If you intend to use a server as a Session Host (like RDSH or XenApp) there is a whole different agent that will probably pass a different set of information to the App Volumes Manager. (look for System Requirements in the User Guide)
I am very curious about your tests because I intended to do the same but the lack of time is pushing me to delay and delay... my use case would be for Writable Volumes for XenApp users (use case would be for Office 365 Outlook cache mode); if you manage to solve your problem like I suggested do you mind letting me know if Writable Volumes work with XenApp?
I honestly don't even know if Writable Volumes are supported on RDSH/XenApp...