Sequence Recorder mishandles certain skeletal meshes when recording.
I THINK this is because of unused leaf bones in the bone hierarchy (See the skeleton tree).
Note: This character is using Set Master Pose Component on the armor meshes. If you disconnect the Set Master Pose Component node and instead use an AnimBP on the armor, nothing is recorded on the armor.
Result: Pants and boots are not recorded properly
Result: Bones are completely messed up
Expected: Bones are in the correct places.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-37825 in the post.