I was following my miner down the shaft the other day and noticed it was leaving behind silver within it's scan range. RP2 copper and tin (and seems like nicolite but I didn't observe) are still actively pursued but not silver. I'm not sure if anything can be done from IC2's end but thought I would let you know.
I'm running latest versions of both mods in question.
You need to add all the RP Ores manually to the miner's Valuable ore list in the config: