The height of the barrier preventing vulcanites from going through structures or objects needs to be tweaked. My vulcanites go underneath the landmark and it makes it hard to see what each vulcanite is doing. Avatar cannot go under the structure/landmark, only vulcanites can. Sidenote- my spy forage, espionage, and regular forage worked fine while vulcanites were underground, so technically it is just a cosmetic glitch.

Link to a video of the gameplay showing Vulcanites going under the Necropolis landmark: https://www.awesomescreenshot.com/video/16945836?key=adb3e5bc5c7b5451d119d193f04caead