Ugh, been there, my autofocus shifts as temp drops.

Saw a thing on a cooking channel about this last month and sort of blew it off, but now hearing it from a real farmer makes me think it's the move. Salting pulls the water out so they don't steam themselves in the basket, which is exactly why your coins were mush in the middle. I've been doing it with cucumbers forever but never thought to try it on zucchini. Cutting them thick like spears makes sense too, more surface area to get crispy. Guess I'm dragging the salt out tonight.

Could you add a pattern too, like stripes or dots?