I'm not sure if this is related to this bug: scirra.com/forum/r57-set-position-to-another-objects-imagepoint_topic44787.html
If i set an object to another objects position, after it passes a certain X position on the layout, it disappears.
It does re-appear if you come back past the point where it vanishes.
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I can't see anything wrong in my dev build, so I think this has been fixed with the other bug.