In this particular alignment there is a tree that blocks the building of the big pole. All the other trees (blocking tracks and such) were removed properly before the screenshot was taken.
Save file, mods are FAT controller 0.2.4, FARL 0.3.14, railtanker 1.0.1, landfill 2.1.5, transformator 0.0.4, rso 1.0.3, and blueprint-string 2.0.2.
Can confirm the same in 0.12.3, using RSO and Marathon. Sometimes shiftclicking does not mark trees for deconstruction. Attached a savefile where a turret from a blueprint does not force a tree for deconstruction.
Noticed the same thing earlier when trying to place a blueprint with many belts and inserters inside a dense forest. Most of the blocking trees were cleared properly and the structures were placed, but some of the trees didn't get marked. Most of the time these trees were sitting a tile away from the structures and just barely blocking the construction area, so maybe there's an issue figuring out whether trees are blocking construction of a structure or not.