I’ve used it for years, thick coats, thin coats, hand rubbed, sprayed on, you name it and I never had it not cure. I even applied it on old surplus military stocks that had gun oil absorbed into the wood that I could not completely remove.
However I agree with the post that said that you are probably applying it over a finish that is not cured. I believe that he said to strip the TruOil you have on the stock and clean it with mineral spirits. I would definitely strip it but would use acetone after that. When I spray TruOil I thin it with naphtha, used to use lacquer thinner but they apparently changed the TruOil formula and it no longer works as a thinner.
Whatever you use, I would take a rather stiff bristle brush and scrub the old finish out of the pores as best as you can and let it dry a day or two before starting again with TcruOil.