Bone snaps back to its original position when setting new keys This is the only blend file that functions weirdly. I am animating a rig and when I grab a bone to move or rotate it, it immediately snaps back to the previous key.

This is what I did:


In pose mode, insert a new keyframe on any bone (let's use root for this example), then move forward a couple of frames
With the bone still selected (again, it's the root bone)
Press G or R to grab or rotate
Press LMB to confirm the translation/rotation
Bam! It snaps back to its latest key (like when you hit RMB to cancel the action)


It would work 'normally' if I hit LMB and then quickly dragged the mouse the side. However, it's driving me crazy and it only seems to be breaking in this Blend file; other files work normally. I also tried to create a blank file to append the rig to that new file, but, the rig still functions weirdly. 

If you guys can help me it would be fantastic :) thank you in advance!

This is the file:
http://www.blendswap.com/blends/view/86352
Another clue, can be an other constraint is on the chain and conflicts.
In this case, you have 2 bones colored in yellow in the chain.
So delete or fit conflicting constraint.