I am making a command pod with ladders and airlocks. Each of the ladders and airlocks use a plain cube, with each mesh collider having 'Convex' and 'Is Trigger' checked, as per the wiki tutorial. Unity imports the model and texture into the GameData without any issues, but in the VAB/SPH the part isn't there. I checked the log, where I found this:
The rest of the log is here: http://pastebin.com/FQxYJQeQ
This is the model in Unity:
As you can see, there are no concave parts in the model, so I should not be receiving the error.