So Markers do have a height Value?

[So Markers do have a height Value?]

So I came across a problem today.

I use Markers in one of my missions to set spawnpoints for loot which is spawned in groundweaponholders.

So far so good. I placed a few thousand of those and one of my friends wanted to help me so he placed some markers himself.

While playtesting i noticed that loot spawned on my markers, spawned correctly on the ground. 

BUT all loot spawned at his markers were like 10 meters in the air.

 

He created his markers on a seperate mission and i merged both together. After i noticed this problem i tried just straight up copying his markers and pasting them into my mission but same result.

The loot spawns, everywhere he created markers, exactly the same distance above ground as if they all have a height value that's 10 meters above 0.

I even went into the map and took one of his markers and held ALT-Leftclick and dragged it like i would if i wanted to adjust its height and it then spawned inside the ground instead of in the air.

 

I'm completly lost as to how i can fix this, without replacing all of his markers.