also on the note of bugs it seams you can buy researches you already completed draining your money.
Noted about the research bug, thanks for reporting in.
About the magnet it has limited range (Magnet range property), item outside the range wont be attracted to. The range unit is in world pixel, you can compare with drill part, each part is 12 * 12 world pixel so magnet range of 24 can attract ore in range of 2 parts. Like I said before most non-magnetic item (copper, gold, sulfur, coal, relics) won't be affected.