The problem is there is no data. I can access data from the phone itself just fine, so I have a cellular data connection. If I disconnect the Nexus 7 and connect to the local wifi network, it gets data just fine, so the device itself is fine. When I try to hit any web page while connected to the Moto X's hotspot, I get the standard "This web page is not available." Trying to ping something from a terminal loses all packets.
It's acting as if the networks aren't bridged/routed properly on the phone. How do I go about troubleshooting this? Are there log files somewhere I can look at?
edit: I should also note that android-wifi-tether, which I used on my rooted HTC Thunderbolt previously, acts like it works fine, but there is no wifi access point broadcast/visible. I have no idea if the problems are related.