Rendered frames don't match viewport action

I’m using Blender 2.81a on a Fedora 30 desktop with an NVidia card & drivers. The Blender version is the one that came down with the distro but I get the same problem with a “full” version of 2.80.

The problem is: The character makes some movement - it looks find in camera view in the viewport. When I render the same frames, the characters arms do odd things.

Another file works fine, so I’m guessing either a setting or file corruption. Anyone have any thoughts?