I just downloaded and installed the addon in the window normally. And it's just not working. That's why I think it's just me, because I haven't encountered a similar problem, and I don't know how to solve it. I'll try more and I can notify you if it's just my error.
Viewing post in Baby 3D Plugin for Construct 2 comments
I tried mismatching the Plane behavior (older version) with the current plugin but all that did was messing up the animations of the billboard.
At this point I cannot reproduce the completely transparent billboards you are experiencing. Unless you changed things in the capx itself, which would be obvious...
Sorry I can't help you any further right now.