I don't have Rex or Zinertek so guess that is unlikely to be the cause. I was wondering, Umberto, if the Key West buildings file could be modified in any way to make it less susceptible or less likely to be in conflict with another MSFS 2020 file? Key West is the only MSFS2020 add on scenery to have this issue as far as I am aware. None of the many other addon sceneries I have has had this issue.