Stables 12 and 21 were a conjoined Stable whose joint experiment was to teach the principles of sharing. For this reason Stable 12 was provisioned to only just support its population while Stable 21 was built and provisioned to be able to support the combined population of both.
Stable 12's purification talismans were pre-programmed to gradually fail and then restart 50 years from the point of complete shutdown. This was done purportedly to force the two populations to share Stable 21 in the interim.
It becomes evident from the recordings and notes left behind that rather than coming together to share for the common good, the population of Stable 12 became xenophobic and paranoid, eventually resorting to raiding Stable 21 and interrogating its populace until unfortunately the Stable's purification talismans shut down and both populations were imprisoned in the cramped atrium of the now unprotected Stable 12.
The Stables were discovered by Hidden Fortune and Lost Art still sealed. Within they found Stable 12 had restarted its purification talismans but all other systems were laying in wait for manual reactivation. They found a large feral population of ghouls sealed in the Stable's atrium and no other sign of life.
Stable 21 was found to be deserted and in perfect condition aside from the damages caused during the rioting at least 50 years prior.