So here's the issue; in an small extension mod I created, I changed the model of the vanilla sc2 structures. While under construction, the building cannot be selected or manually attacked. This is especially bad when I halt construction of a building and cannot finish it, or when I cannot rally workers to a gas mine while the building is under construction. After construction, however, the building is selectable and works as intended.
Two important things:
-The models used are almost always doodads.
-If you play as the zerg (Underworld) and you keep your selection on the worker before and during it making a structure, a blank icon will appear, along with the description of the worker unit, and not the building. This is true for morphs as well.