I got this:
An error occured during GHA assembly loading:
Message: Could not load file or assembly ‘file:///C:\Users\j.hutchinson\AppData\Roaming\Grasshopper\Libraries\Fattener.gha’ or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)
Message: An attempt was made to load an assembly from a network location which would have caused the assembly to be sandboxed in previous versions of the .NET Framework. This release of the .NET Framework does not enable CAS policy by default, so this load may be dangerous. If this load is not intended to sandbox the assembly, please enable the loadFromRemoteSources switch. See http://go.microsoft.com/fwlink/?LinkId=155569 for more information.
Loaded up Rhino WIP, Grasshopper, dragged and dropped to special components, unblock, restart. Grasshopper has Mesh Cage Morph from Fattener V 0.0.0.1 regarded as unknown.
Edit - Okay got it, I had to zip it up as a workaround to getting an IT guy to download it for me. Unblocked the zip rather than unzipping and unblocking the gha. Does that sound right, or was that just a chance circumstance?