This problem still hasn’t been fixed.
Some buildings either can’t be built, or rooted in explored fog of war. It’s something that has been an annoyance for a long time.
Here’s the list of the buildings affected, taken from Maguro’s Bug Hunt III, where he incidentally also suggests a solution to fix it:
The suggested fix:
in Pathing Footprint (Placement):
uncheck “fogged” in PlacementCheck/SetOne/Invalid
in Pathing Footprint:
uncheck “fogged” in PlacementCheck/SetOne/Invalid
Buildings that cannot be built in explored fog-of-war :
Primal Wurm
Spore Crawler
Spine Crawler
Infested Missile Turret
Buildings that cannot be rooted in explored fog-of-war :
Spore Crawler
Spine Crawler
Infested Missile Turret
Infested Barracks
Infested Colonist Compound
Infested Factory
Infested Starport