Not using the whole tank of fuel - E46 330d

Recently bought a 2004 E46 Touring 330d, the car seems to be in excellent condition with some minor things to fix.

The previous owner told me that the fuel level sending unit is bad and that after the car passes 1/4 it's basically no fuel.
I've been driving the car for more than a month and always filling at 1/4 and noticed that I have more than 15l in the tank.

So yesterday I was driving and decided to test the fuel economy and the fuel level sending unit, per my fuel economy and CPU I had around 150km left to drive.
Exactly in the middle between empty and 1/4 the car died. I had a friend bring me 10l of fuel, put that in the vehicle and visited a fuel station nearby, the car fit another 43l.

10l of fuel do not get picked up by the fuel pump and the fuel level sending unit seems to be correct?

What could be the issue here? Has anyone experienced something like this?