Hello Allan, can you reconstruct your connection and give us the complete link from the broesers address bar?
I 've seen a partial connection of the Connection Finder as blood relation via A and her son B and his sister C. I was a bit astonished, but C was not the daughter of A, only the daughter of B's father. Maybe the Relationship Finder would have problems with siblings or half siblings.
Another question would be, how adoptive connections are handled.
Edit: Ahh, your image came in the same time … There are also sibling steps, which can have problems …