Last night I finally found some of the areas I builded some years ago, but opening them in the toolset, apart from the fact that all placeables were gone (I used a different module with a different 2da custom placeables list), I have this wierd bug: exterior areas are considered as interiors, so in the area there's not the exterior grid and the walkable square, but there's the interior grid, where tiles should be put. Obviously, being an exterior area, I don't want to put tiles at all, just want to have back my walkable squares I had. Someone knows if this is possible and how to? Thank you.
Here's a screenshot of the tile grid in the exterior area:

Remember them all it's just a game.