I created a very simple test-scene to isolate this problem: one character (generic rig) on a simple plain, with an Animator controller that defaults to a simple walk animation with root motion. None of the gameobjects have any custom scripts. In the editor and in my Android builds, the character moves forward as expected. But in WebGl builds, the character is animated in-place; no root motion is applied.
Is this a known issue, or should I file a bug report?