Win/Wobots do not add items into icker preserves

I wanted to try doing something fun with winbots/wobots to store normally spoiling items into containers. While you can do this with chests and iceboxes, the items inside will lose quite a bit of spoilage and you always need at least 1 item inside for it to deposit items into the containers. I thought icker preserves would be a fun way to work around this, but it seems they do not register it as a container they can deposit into at all.

(Example of it not reacting to a 15 stack of MM on the ground when there are 5 in the preserves) 

The same issue happens with wobot, which makes sense given they share similar code.