Descriptive Problem Summary:
When object instances is set to classic mode pixel_x/y/w/z offsets are applied inversely of the original offset every time the object is deselected by selecting a different object.

Numbered Steps to Reproduce Problem:
Set Instances to Classic mode in the map editor
Place an object on the map
Edit any of the object's pixel_x/y/w/z variables to a non-zero value
Place a second object on the map
Make the first object the active object
Make the second object the active object
The first object will be offset by the inverse of its pixel_x/y/w/z variables
Repeatedly swapping between them will continue to additionally offset the object