It just breaks the market for me. Idk if it's because of an update, but the market appears as either some building with glitched text that I can't move around, or a black void of a card.

interesting choice, First run I ended up with 3 markets into 3 chests and was making so much gold by overproducing food it was quite ridiculous reaching over 200 gold and once I ran out of stuff at the university? I realised that the 50 gold for the idea was not endless, I like this better instead of the micromanaging of 3 at once

will this boost the range of the resource magnet?

Are you saying if you put two markets on top of one another they run twice as fast?