You need him as master, then he should ask you to bring him the ores
Try holding >=10 iron first, then silver, then gold, he should give you the recipe
Are you playing R21
I think you're not right! Got the same issue! Can't provide any ores to Derek. He's always asking for a golden pickaxe.
You can choose Derek as Master after you delivered 10 ores of each metal.
In the cave I found 8 bombs in chests (1st chest in 2nd room/route north, clear the entrance of next room and find 2nd chest).
After I got them I went back to the farm and cleared the entrance of crystal cave (there was another bug "Objektive: undefined). Then went to Nina to see Nina's scene in cave.
After this scene I went back to Derek, but no chance to give him any ores . . . it's frustrating!
Playing any other route Derek takes ores and gives recipes. But he only gives 1 recipe (standing torch).
The only option is to cheat: enter higher number of bombs in inventary or select item 644 in "switches", but I don't like this. After selcting I receive the bomb recipe. But it looks like crap! See picture (rock and iron ingot as recipe content - ridiculous!!).
Hopefully these issues are sorted out with next release.
Cya