(KS7) ground material doesn't render properly

[RRIS]

I'm on the last KS7 update, trying to render a wall-mounted product. Now, the renders have to be on a clean light gray background, so to get some shadow, I've placed a wall surface behind the product and given it a ground material so I just get the shadow information.
I'm rendering in product mode with a few GI bounces. Now I've set up a bunch of studios and I go through all of them and send them to the network to be rendered on our dedicated machine. The problem comes when I cycle through the studios and press 'send to network' too quickly. Somehow in the viewport the drop shadow on the ground material doesn't materialize until I hit about 4 or 5 samples and this takes longer than it takes for me to cycle through the studios and send the renders to the network.
Somehow this causes the shadows and ground material to not render at all.
I HAVE to wait until I get them in my viewport before sending out my renders to the network, which is incredibly tedious..
What's going on?