Getting 'Render engine not selected' on the primary machine after attempting to kick off a cycles render. The primary machine seems to be trying hard, but the second one isn't doing anything. The Crowdrender panel suggests they are connected correctly, but it just doesn't render anything.

This is Blender 2.78c, CR 0.1.1, Win 10.

I made sure the render was very lightweight (1 sample, only a few hundred pixels wide) but still no results.