"Unconventional Inspiration (Ex): An investigator can pick
any one skill that he is trained in but that he can’t use his
inspiration with. He can use inspiration with that skill. An
investigator must be at least 17th level to select this talent."
This ability, as written, does not seem to do anything at all. An investigator can already use inspiration on all skills at first level. Am I missing something here?
Yup, that does seem like a bug. Maybe it was intended to allow you to use the skill without expending a point.