Grasshopper components missing in v6

I’m having some problems with Grasshopper add-ons using the Rhino v6 WIP. Some components (eg Element*, Elefront) do not show up in the ribbon but I can create a custom ribbon layout and add them. I can also find these using the double-click search. Other add-ons (eg Honeybee, Ladybug) show up in the ribbon but components/user objects do not. These can also be added manually and located via double-click search. Lastly, some add-ons (eg Tree Sloth) are not found at all.
I’m running Work In Progress (6.0.15216.5391, 08/04/2015).

This might be similar to the component location issue Mitch notes here:

After seeing that, I’ve tried locating the GHAs &c. at both the v5 and v6 locations:
C:\Program Files\Rhino WIP\Plug-ins\Grasshopper\Components
But this does not seem to have any effect. Also, I have verified that they are unblocked. The add-ons all appear and work normally in v5.

Any advice?