Actual towing nose weights on a twin axle.

I have a twin axel van which i can load to the recommeded nose weight using my milenco measurer.

However, the van seems to  naturally sit on the axles, a little higher than the tow ball on the car, to the point at which the jockey wheel will come off the ground sometimes and i have to push the hitch down to get it to snap on. I have a fixed height removable tow bar.

I suspect the actual nose weight is down at 10-20kg tops.

Anyone else experienced this problem? And is it a problem?