This is not a feature, so it must be a bug. Mice are able to eat your crops, so make sure that's not the reason. I'll look into it when I have time. Please tell me if you have any more information on bug.
The mice eat the plant, and then you have to start over, or kill the mouse before it eats the plant. They shouldn't be able to hide under the crop plots, but I'll look into it in the weekend, when I have time. Thanks again.
