Follow Path changed between Blender 2.80 and 2.81? New bug, or bad model?

I have a model character that works as expected in Blender 2.80 (walking along a path), but falls flat on its face in 2.81 and since. Can someone tell me whether this is a bug recently introduced to Blender or a fault in my modelling? The model is attached. Thanks in advance for any insights!
walker_(Arnold_Smith).blend (846.3 KB)