Allright... I figured this out --- I even opened up a support ticket and they weren't able to figure it out. So...
long story short The "Hyper-V" setting for the "iGroup" and the the "OS Type" when you create the LUN should ONLY be used when you are using NetApps Managment Applications like SnapDrive... If you just want to run the native Microsoft solutions you must use the OS Type of "Windows 2008 or Greater" which means the iGroup needs to be Windows...
I was runinng Hyper-V 2012 R2 and now Hyper-V 2016 since they both support the inline SCSI unmapping that works automagically (no additionally software needed). The only additional thing that must be changed on the NetApp side is the "space-allocation" option must be enabled on the LUN, its disabled be default.
So if you need to run the Powershell tookit still it should run after these settings although you shouldn't need it...
If you need to run unmapp in Windows forcefully you can just run
Get-Volume
This will list all volumes (make sure you are on the host that owns the Volume)
copy the label and run this command
Optimize-Volume -FileSystemLabel <Label Name> -ReTrim –Verbose
example: Optimize-Volume -FileSystemLabel '3TB Test Volume' -ReTrim –Verbose
Here is some links that help me get to the solution...
Scroll to the "LUN types to use for hosts and guest operating systems" section
https://library.netapp.com/ecm/ecm_download_file/ECMP1656701
This article talks about the "space-allocation" option
https://library.netapp.com/ecmdocs/ECMP1196784/html/GUID-6AD84908-041A-497D-95A7-BB6AFDD1B282.html
I hope this helps save you from the months of frustration it caused me...