_Grasshopper doesn’t reload VisualARQ components after _GrasshopperUnloadPlugin command.
They are gone. You must restart Rhino.
This is a known issue, but as
GrasshopperUnloadPlugin command has been problematic, it had been removed in Grasshopper 1.0 (included in Rhino 6) almost a year ago. We have no plans to fix it.
May I ask you: why are you using this command?
I used _GrasshopperUnloadPlugin to reload .gha libraries without restart Rhino5.
I never notice because I never developed for Rhino6.