Printer head too low when printing
Did you verify the Cura z-offset actually changed the corresponding G-Codes? 

I had the opposite problem on my RF1000. To fix the problem I added the following 2 lines to my start G-Codes:

M3001 ; Activate Z-Compensation 
M206 Z-0.3 ; Set z offset 0.3mm closer to the nozzle


The first line was default in some example prints and is (as far as I know) only used by Renkforce printers. The second line moves the nozzle closer to the bed. In your case you'd have to move it further away and would need a positive Z value.