Try going into your settings menu, then under Mobile Networks, toggle the LTE/4G option off them on again. You can also try booting the phone without your SIM card, them reboot with it back in. It might shake things loose.
Sent from my DROID BIONIC using XDA App
Both seemed possible; neither worked.
When I reboot, the 4G logo/icon appears in the top status bar. If I try to load a webpage or use the network connection at all, it says no network available, and 30 to 45 seconds later, 3G is up and running (walking, really). Frustrating!