Z home pronterface works, G28 Z0 makes Z movement freeze

Hi,

with a lot of help on this forum and some tinkering I got my RAMPS 1.4 (24V) with TMC2130 V1.1 stepper drivers and Marlin 1.1.9 working. As sensors work, all axis and the extruder move as they should. Homing X and Y works (no sensorless homing, yet, just micro switches). Z has an inductive sensor, sensing the alumunium plate bed, and that works too.

But I have trouble homing the Z axle when using Marlin:
- When I ask pronterface to home the Z-axle, using the little house button with the Z in it, it works. First a fast sense, then a slow and accurate final sense.
- When I ask Marlin to home the Z-axle, either solo or with all three axis together, via G28 in Pronterface or giving the homing command on the RepRapDiscount full graphic smart controller, it moves away from the sensor a few mm and then freezez. After a while, I get the message "Homing failed" and I need to reset. Trying G29 (I have set it up for 3-point sense) gives the same result. It moves to the first sensing location and then it freezes when the bed wants to approach the sensor.

I cannot figure it out, can you? All help is appreciated.

Cheers,

Hugo