Suspension lop sided (4 bag)

[Hermjeji]

So, have a 2004 T800 dump truck with a neway 4 bag 46k suspension. It has only
One levelling valve, and was recently replaced to try and solve the symptoms I’ll describe below. Obviously it is not fixed yet.

When empty, the suspension appears straight (ie. on level ground)

As soon as there’s about 3-5 tonne of a load in there (13 tonne legal) you can see the passenger side does not want to inflate as much. It ends up at full load having about 3-5inches of drop
On the passenger side. The air bags don’t appear to be damaged, and they all are the same bag. No leaks at the bags.

Appreciate any experience you’ve had to sort these straight.