Looks like the exact same problem for me!
when i set scale layout to 2 and more, my character animations begin to stutter in a strange way. There's like 1 px shaking on the animation. Am i doing something wrong? My character is a 32 x 32 sprite attached to an invisible behavior sprite. When i reduce the scale, it behaves normaly. Is this a bug??
In the meantime, i found out that pixelrounding OFF does remove it. However i have to test it some more, but for now it looks smooth.