Thanks for testing it out. I'll probably need to purchase an Onyx in order to debug the issue.
Viewing post in Onyx+ not working with v0.9
Ok.
I suppose you know the buttplug sdk : https://github.com/buttplugio/docs.buttplug.io, Maybe it could help you. Unfortunately it doesn't support c++ yet and I suppose you're working in c++ with unreal.
Thanks anyway!