Forge-Kill boundaries not working on invasion

So, I’m making an invasion map and I think I have a reasonable idea of how to make a map work for invasion, I got my objectives, weapons, vehicles, spawns etc. all linked to specific phases and the map works fine on custom games.
However, then I try to use soft kill boundaries to section off areas of the map to fit each phase and I’m running into problems. I’m on forge world, and since the map shape is a little complex, i thought it easier to make the whole map boundaries out of soft kill zones not tied to phases, i.e they’re always there no matter which phase the game is at. Now, I’m using soft kill boundaries to make the final phase (3) be played in a different part of the map to the other two.
My way of doing this is simple, just putting a soft kill over the phase 3 area and setting it spawn sequence 3 and inv gate, and putting a soft kill over phase 1+2 area and making it inv-weapon (they both have spawn time set to 1). However, this doesn’t work. the phase 3 area starts off as a kill zone (good) but then stays there during phase 3, making the area inaccessible (not so good) and the phase 1/2 area doesn’t spawn initially (good) but then doesn’t disappear during phase 3 (not good-can’t be having people run back and taking say, a wraith from phase 2 and using it in the close-quarters on foot phase 3 bit).
I’m scratching my head a bit here, I don’t know why this wouldn’t work… any advice is appreciated😊