• Description: When settling on a former IP territory who vanished, districts' ruins from the IP city are build-off-able.
• Steps to Reproduce: 1. Start the game 2. Launch the savefile 3.  Select a district to build in either Tik'al or Parisius (Farmer district for instance) 4. The placement tooltip in Tik'al will advise placing the farmer district on a tile adjacent to a ruin. 
• Reproducibility: 5/5 - Placing districts adjacent to ruins is consistent on both cities territories mentioned.
• Expected Behavior: Ruins shouldn't be build-off-able obviously.
• Notes: The actual ruin district (from where the farmer district can be built) is not visible on the map, but hovering the mouse over the tile shows it's a ruin (screencap below of previous IPs cities for districts placement reference). The same goes in Parisius (there's a missing ruin visual).
• Attachments:

Ruin visual not appearing, but build-off-able (tile highlighted with a black hex) :

Ruins layer (ruins districts appear a bit clearer on this zoom out view) :

RuinsBuildoffable.ctr

For comparison and reference in IPs districts placement, here is the 2 IP cities before they vanished :

IPsCitiesBeforeRuins.ctr