More Words, Deeper Hole

Well, not having been able to get any has more to do with not having found a reaction which will produce the potentially stable isotopes in the first place. Thus far there has only been a dozen or so atoms of ununquadium produced, (all in the 286-289 mass range, not the possibly stable 298), there have been claims of 2 atoms of unbinulium, (again too light to be stable), and no unbihexium has been produced.

For natural production, remember that most natural production of heavy elements is by neutron bombardment and that getting to the island means running a gauntlet of mili and microsecond half lives. It might not be possible to get there even with the r-process.