It's probably caused by the whole outer shape having a single snap info (so it also snaps into beam holes). The shape/size of that info (bounding box) makes it more likely to 'win' the connection tests.
I'll see if I can improve that behavior somehow. If it really bothers you you could replace the outer shape by just a simple stud one.
I'll see if I can improve that behavior somehow. If it really bothers you you could replace the outer shape by just a simple stud one.