ID:1971334
 
Resolved
Images added to objects that the client could already see on the previous tick, did not persist and disappeared as soon as the object left the player's view.
BYOND Version:509.1310
Operating System:Windows 7 Ultimate 64-bit
Web Browser:Chrome 46.0.2490.80
Applies to:Webclient
Status: Resolved (509.1312)

This issue has been resolved.
Descriptive Problem Summary:

When you create an /image type that overrides a mob's (or anything's) icon via the atom.override member, to hide something from specific players, the image will disappear and the mob will become visible when the mob is no longer in the client's screen, then at any point re-enters it.

[A gif is worth 1000(frames) words!]
This isn't new to 1310, right? (Seems like it'd at least be 1309 if not earlier.)
It's not, no. I think it's been happening since before 1309, as well.
Something else has to be going on here, because I can't reproduce this. I'd look at the source, but I can't find this quest in any of the source I have, so I might need something newer.

What I tried specifically was setting an image with override=1 that also changed the icon. (I also tried various other image permutations, including override off and no icon change.) At no point did the image disappear and fail to reapper.
Lummox JR resolved issue with message:
Images added to objects that the client could already see on the previous tick, did not persist and disappeared as soon as the object left the player's view.
Nice!