Okay, first I know this question has been asked - specifically here: Live preview not automatically updating
But that suggestion did not help. I have no console errors, no network errors. In fact, when I view the network tab in Chrome I can see it successfully POSTing the changes as I type in live preview mode. I have this set up on MAMP using craft.dev as the hostname.
I tried this in both Chrome and FireFox with no luck, as well as trying a fresh install of Craft with no success.
Any thoughts are greatly appreciated on what the issue might be.