Current questions and answers regarding the map editor.

Open the editor again and enable the display of traversability (one of the buttons at the top). The map will immediately be colored in red, green, and possibly semi-transparent yellow. If a cell is not colored, it is completely traversable. If a cell is red, it cannot be traversed. Either there is an object blocking the way (the object needs to be removed), or it is flooded with water (you can swim across it, or you need to remove the water). If a cell is yellowish, a mask has been applied to it, making the cell impassable. There are other tabs next to the objects tab, including a special one for masks. Enable it, activate "erase," and remove any unnecessary masks. If a cell is green, it is most likely impassable (exception: a garrison), but you can interact with it. It is best to treat it like a red cell, i.e., remove or move the object. Lastly: changes in traversability are not immediately visible. You need to disable the display of traversability and then re-enable it; then it will become clear whether the problem has been resolved or not. That's all.