No it is happening too often for that.
I suspect that if you do not click on one of the names that iSpot offerrs and instead just type in the name and move on, then iSpot does not link it to the dictionary. But it is not as simple as that, becuase sometimes it does work.
Simply there is a bug. Names that are in the dictionary are not being linked. Riaan has played with this and suggests that it is a problem with the common names. Because the new iSpot links the common name to the scientific name in the selection menu, if you do not choose a common name, then iSpot does not know which of the many identical common names to choose from and it does not choose any.
But it cannot be as simple as that, because some of the names not linking dont have any common names ...