For anyone who might still be using this script or a version of this script. If you are having trouble with floating loot near the map terrain you can comment out line 85 in LSS_fnc_spawn_loot_inBuilding.sqf
// if (_lootPosition select 2 < 0.5) then {_lootPosition set [2, 0.5];};
This line is updating the z position (height) automatically if it's under 0.5. For my example, there's a bunch of buildings inside Chern Redux that have floors under 0.5. Disabling this fixed my floating loot.
I also paired this with changing the createVehicle object to "GroundWeaponHolder_Scripted". Hope this helped!