Fixed #3206

core/src/mindustry/io/MapIO.java

@@ -79,6 +79,11 @@ public class MapIO{
             CachedTile tile = new CachedTile(){
                 @Override
                 public void setBlock(Block type){
+                    //previous state.
+                    if(build != null && build.block instanceof CoreBlock){
+                        map.teams.add(build.team.id);
+                    }
+
                     super.setBlock(type);
                     int c = colorFor(block(), Blocks.air, Blocks.air, team());
                     if(c != black){
@@ -86,14 +91,6 @@ public class MapIO{
                         floors.draw(x, floors.getHeight() - 1 - y + 1, shade);
                     }
                 }
-
-                @Override
-                public void setTeam(Team team){
-                    super.setTeam(team);
-                    if(block instanceof CoreBlock){
-                        map.teams.add(team.id);
-                    }
-                }
             };
 
             ver.region("content", stream, counter, ver::readContentHeader);

core/src/mindustry/maps/Map.java

@@ -74,7 +74,7 @@ public class Map implements Comparable<Map>, Publishable{
     }
 
     public Fi cacheFile(){
-        return Vars.mapPreviewDirectory.child(workshop ? file.parent().name() + "-workshop-cache.dat" : file.nameWithoutExtension() + "-cache.dat");
+        return Vars.mapPreviewDirectory.child(workshop ? file.parent().name() + "-workshop-cache.dat" : file.nameWithoutExtension() + "-cache_v2.dat");
     }
 
     public void setHighScore(int score){