Shifted windows follow when switching between multiple desktops

[raldred]

I'm using multiple desktops (formally spaces) Shifted windows have started following me when I switch desktops, I'm sure this is something recent, as It used to be ok.

MBP Mid 15 using external Monitor OSX 10.12.3 Shiftit 1.6.3

Example: On Desktop1 I shift a window to the left half of the screen (Ctrl + Alt + CMD + Left) Switch my screen to Desktop2 (Ctrl + Right) the window doesn't remain on Desktop 1 it's brought over to Desktop2 (it remains on the left half of the screen)

If I manually resize the window it stops the above behaviour. i wonder if the window is overlapping the edge of the screen slightly.