The "has an Embassy with" relation is not symmetric. As of this morning's dump (and game reality too), The Black Hawks has an embassy with United Defenders League (no The), but United Defenders League has no embassies with anyone. This assymetry (in general, not this specific one) causes certain algorithms involving connectedness of regions by embassies to produce different results depending on the direction you go in.
If I had to guess, I'd say that termination of an Embassy doesn't always get cleaned up on both sides.
I don't know if existing instances of the problem can be cleaned up or not, but if it can at least be determined how it happened, then possibly such algorithms can know how to cleanse the data themselves before getting into trouble, and perhaps the creation of new anomalies can also be avoided...