Indeed, I recreated the map and regenerated this piece of map, the structures have disappeared, so this is a bug that appeared in a single generation, but that has happened to me
The bug map : https://www.dropbox.com/s/xg04t96rvppjss6/test%201_13.zip?dl=0
I have tried with less busy computer/game and all run correctly, i go modify my system for support that, thanks for help.
We can close this report.