During mission “Armonia delle sfere” , the target of the mission was to recover something for the first floor of a building.
The floor tile with the mission target was destroyed by a missile, and the “highlighted” target square seems to be moved on the corresponding ground tile.
However when sending a unit on the tile, it is not possible to trigger the target.
I guess it would be also fine to get a “mission failed” when it is destroyed, but in this way it is not clear.