First layers okay, but a scratching nozzle off 5cm and more

[busch3d 0]

Good moring from Germany. 

My prints with my UM2+ and Octoprint are good - but I have one mystery. 
My first layers are beautiful. But after about 5cm the nozzle is scratching on the printed object. Like the z-direction ist not lowering the buildplate enough. 
It's okay when I print an object, which has a good sticky stand on the plate. When not, the nozzle is kicking it away. 

Of course I did a buildplate leveling - but the result is the same. 
And it doesn't matter if I print left or right, front or back - always the same problem: Scratching nozzle on the object after some cm....

 

Has anybody an idea what I should do next - or did anybody had the same problem and has a solution for me?

 

Thanks, Holger

[gr5 2,234]

Is this happening on walls that are tilted?  Overhangs?  if so then this is very common and you can probably ignore it.  The cure is usually more fan but by default your fan should be at 100% already so you can probably ignore it.