Version: DOW1 GOTY (Steam)
In mission 1 you receive a "primary" goal to build a listening post. The first time I played this mission, my servitors did not have the button to build listening posts, even after reloading a savegame.
This revealed a second glitch: Even though building a listening post is a primary goal, you can complete the mission without doing so.
Restarted the mission twice, afterwards. Both times my servitors had the build listening post button.