Can't get a shadow? Problem! (Project included)

Shadow Problem Project

So, I’m working on a project where I need to render out some shadows on a transparent image so that I can composite and adjust them later in After Effects. The problem is Blender is choosing not to render out any shadows on a transparent plane.

Above is the project file where you’ll see a model of a tank on top of a ground plane. The material for this plane is set to “OnlyShadow” which is supposed to only render shadows that are cast onto it, however for some reason it’s not. I’ve gotten this to work numerous times, but for some reason this project just will not. Even if I open a new project I’m able to render out shadows the same way I’m trying to do in this project.

I’ve tried everything, played with render settings etc. and cannot fix this. Would anyone care to tell me what’s going on? I’m starting to think it’s just a corrupted Blender file.

Thanks in advance, and let me know if you have any questions.