[1.5.2] Infinite Dungeon mirror clone challenge not found

[Zeyphor]

I was doing ID just earlier and got the mirror clone challenge, but I couldn't find the mirror clone even by after autoexploring, digging around in a slimy slumbering cavern-like level, so I just went to the next level and looked for something to hold 5 next to so I could die
another guy in chat implied that this bug is quite frequent

[TarquinMitzi]

Having the same issue.

https://pastebin.com/3aDpZVJ0

Mirror Challenge can't be found on the map