Win7 GTX 770
If you move multiple objects that have motion paths, only one will update it's keyframe and motion path correctly.
The other objects with motion paths, will reset as the you never moved them, then insert the blank keyframe.
This file has 3 cubes selected with only 2, using motion paths.
If you move all 3 cubes, only the cube without a curve and one of the others will stay moved.
If you add a motion path to the middle cube, and move all 3, only one will stay moved.
This doesn't happen with bones in pose mode.