Set internal cargo; Can't seem to get it working

[Nealius]

I'm trying to make a simple mission whereby I fly from Batumi to an LZ, pick up cargo, fly back to Batumi, and unload.

 

Load cargo trigger:

 

1 Once (LZ, No event)

>Unit inside zone (UH-1, LZ)

>Unit's vertical speed in limits (UH-1, -1, 1)

>Unit's altitude lower than (UH-1, 60) > Set internal cargo (450)

 

Unload cargo trigger:

 

1 Once (RTB, No event)

>Unit inside zone (UH-1, RTB)

>Unit's vertical speed in limits (UH-1, -1, 1)

>Unit's altitude lower than (UH-1, 60) > Set internal cargo (0)

 

But it doesn't seem to do anything. It feels almost like the helicopter starts off the mission with 450kg of cargo judging by needing 95% Gas Producer just to hover at 5ft.