I finally found it progressing... it only counts criminals the player uncovers themselves so requires a lot of RNG and luck finding arriving guests who are actually criminals. If it was 5-10 of these it wouldn't be so bad... but 30 is really overtuned and very tedious sapping the fun away from the rest of the game.
At the least the text of the objective should reflect that it is manually revealing criminals only that counts, and it really should be fewer in that case.
I am on the science museum map working on my second star.
I have built a few Panoptic Pillars and placed them strategically around the museum, including at the entrance before any guards have a chance to discover thieves themselves.
I have pinned the objective to "expose 30 criminals" to keep an eye on progress.
I have had a pillar alarm at least once.
I have had guards expose criminals and my monthly report shows criminals exposed.
I have not been able to expose a thief myself via random guessing of visitors and drenching them.
The quest has not increased in a single count in hours of gameplay, and with guards exposing multiple criminals.
Either this is very ambiguous and poorly worded on how to unlock the pristine Panoptic Pillar or the counting of exposed criminals is just broken.