It would appear you are correct. Part of your case is broken. Maybe hit something on the road? The only fixes I can think of require the engine to be removed from the frame at least. The bolt boss could be welded up, machined flat and drilled/tapped for the bolt. If you are only losing a few drops I would just put a piece of cardboard under it for now. Someday you may have to pull the engine and can deal with it then. Maybe even just get a used side case for cheaper than paying a machine shop. I wouldn't try it at home. Sorry, maybe someone else will have another idea.
If you check Roach's rebuild video, Pt. 6 when he splits the case, at about 3.07 minutes, you can see what it should be.
No Brain - No Pain. I measure a man by the good he does for others, not his mistakes.