This is a regression. Tested in //UE4/Release-4.27 CL#18319896
Moving widgets within UMG by dragging the position value with any sort of speed results in the widget stuttering and jerking around.
As in 4.27.2 the widget should smoothly slide back and forth.
The widget stutters and jerks around.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-160414 in the post.