You have a case of the f��loppy bucket you have some air in the hydraulics and the weight of material in the bucket is pulling the bucket down.
Try this to correct it, with the bucket empty and the loader high enough, so you can dump the bucket completely without hitting the ground. With the bucket curled all the way back, push your joystick all the way to the right as far as it will go, so it goes into regen/fast dump. Do this a couple times and you should be good to go.
Someone else wrote the following, it should help explain what regen is.
Regen is a "feature" of most modern FEL (Front End Loader) valves, it's on the Dump (joystick far right) circuit, and is also referred to as "Fast Dump". The reason it is nice to have is that without it, the weight of a filled bucket can actually "pull" the bucket down faster than the fluid can enter the other side of the cylinder, this will create a air pocket and give the bucket a "floppy" feeling until the joystick is held in the dump mode a few seconds to refill the cylinder pushing the air past the seals. So we add "regen" or "regenerative" function to the valve.
Regen solves this problem by actually filling both sides of the cylinder at the same time with hydraulic fluid. But how will that work you might ask? Well, because there is more volume on the side of the cylinder that extends it since the rod is taking up space in the other side, it "overpowers" the rod side and lets the cylinder extend-thereby dumping the bucket. So since now both sides of the cylinder are "pressurized", the air pocket can not develop, eliminating the "floppy" bucket syndrome. One other added bonus is that the bucket actually dumps faster due to the higher flow rate required to do all this, that's why it's referred to as "fast dump" sometimes.