If you're getting this error regardless of the faction you're using, I'm going to hazard a guess that you've somehow restricted the module from populating objects. There are a few things that can cause this, but first things first, find the exact module which is giving you this error (meaning, delete it, start the mission, and make sure the error goes away).
Once you find the module that is the problem, look at:
1. Your blacklist and whitelist lines. Make sure the area you're letting your units spawn...the whitelist..has compatible objects within it. So military objects for the Military Objective module and civilian objects for the Civilian Objective module.
2. Make sure the module itself is literally sitting on top of a like object. The Military Objective module needs to literally be placed on top of a military object and the Civilian Objective module needs to literally be placed on top of a civilian object. You can see where the objects are by turning debug on in the module, starting the mission, and looking at your map. If you do this, make sure the blacklist and whitelist lines are blank. Make note of a compatible object from the map in game, go back into the editor and literally place the module on top of the object.
3. Make sure you're not filtering the priority too high. If 1 and 2 are ok, you can still be having issues because you set the module to ignore small and medium objectives. Try "do not filter" first and see if the error goes away.