Hi Paul,
I'm sure you've got your hands full with other things, but I've found that the current plug-in build crashes ArchiCAD trying to activate. It's fine if the licence is already active on the PC, but if it need to acquire an available licence, ArchiCAD crashes to desktop.
The only way I can activate Octane for ArchiCAD at the moment is to have one of my older ArchiCAD's (v19 in this case) still on 3.07, so I can use that build to acquire the licence, then switch to AC20 or 21 on the 3.08 build and it doesn't then have any issues because the licence is already active on my PC.
Hope this makes sense?
Cheers, Dan.