It is hard to say if abilities work since everything is still random.

Eg. Rank 38 Miner gets HQ Cobalt ore. Me, as lvl 50 Miner, same point, with rare items ability on, get 0 HQ cobalt ores.

Since it is not 100% with an ability on, it is really hard to notice if any of them actually work.

King's Yield - definetally doesn't work on Mythril, Electrum or Cobalt ores. I think it should, since they changed the yield rates on these types of ores.