This is a previous, and likely well known bug, but I'm mentioning it cause it's still an issue. After respawning from death, your animation is permanently frozen, no matter what you do.

I had an issue with character freezing as well. Though it wasn't immediately after death, but shortly after respawn. I was running across the grass away from the spot where you respawn, and tapped the 'walk' button, and suddenly my avatar froze.