Descriptive Problem Summary:
If you attempt to place a turf on a different z level in an image's vis_contents, it will break.
Instead of displaying the turf, it will display the turf at that x and y position on YOUR (the viewer's) z level.

This does not include the turf's contents, that is mirrored over just fine.
I hate it here.

Numbered Steps to Reproduce Problem:
Create a target turf on a z level not the same as a viewer turf
Create an image with a "loc" on the viewing z level. Point its vis_contents at the target turf.
Behold suffering

Code Snippet (if applicable) to Reproduce Problem:
See this branch, you'll want the latest commit

Video example here
The primary thing to note is there is a "cookie" on the same tile as the turf being mirrored from above, it's just not visible in the map editor because of layer things

Expected Results:
The turf on the upper z level will be mirrored down, as is expected

Actual Results:
It is not.

Does the problem occur:
Every time? Or how often? Every time
In other games? In my experimental ss13 code
In other user accounts? No clue
On other computers? See above

When does the problem NOT occur?
Never?

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked? (Visit http://www.byond.com/download/build to download old versions for testing.)
Unsure

Workarounds:
Don't use images. This is not always acceptable