I don't understand what a window has to do with it?
The marker for "disable the security matrix" appears on a partially-covered open platform. When I get to the platform I can no longer bring it up by pressing the objective button and there is nothing I can interact with, but it still appears on the map.
Edit: I get it now, thank you to all who answered. 🙂
Apparently you have to go around behind the two locked rooms at the beginning of the level and there's a thing you have to be incredibly prescient to know to scan for in the top room. Then you get a hint to check the lower room and theres a machine you can interact with. That somehow triggers the marker on the platform to appear assomething you need to scan for.