My previous truck had the same issue.
Aldough it wasn't air-ride or a Volvo,there was a lesson learned in solving the problem.
Like the OP i went to a alignment shop ,they did their thing,truck pulled to the right like you wouldn't believe.
It was actually worse then before.
Went back to that shop,they redid it,no use.......said they had done all they could,wasn't fixable according to them.
Then ,on the advice off a friend,i went to a place where they did mainly chassis alignment,basicly they straighted wrecked trucks.
As a side bussiness they did "normal" alignments as they had the equipement allready and could generate extra cash with it.
They found out that my axle wasn't bent correctly at the right side(just past where the spring is,where the S curve is)
With them having the heavy duty equipement for straighting chassis,it was very easy for them to bent the axle to the correct position.
So in short my advice,maybe go to a shop where they straighten truckchassis as those guys have the equipement to measure and if needed bend your axle to the correct setting.
ps if your axle does need bending,pls go to a very good workshop as bending any axle is a delicate operation,no room for the slightest error.