How come firmware isn't uploaded? I am calibrating my Kossel XL with a new Marlin firmware changing the MANUAL_Z_HOME_POS since I have modified my print bed.

I change the value in the Marlin code and upload it through Arduino (the editor on Windows 10). It has worked many times before with the exact same version of Arduino.

When I then use Pronterface and issue G28 (home all) followed by G1 Z30 (just to be on the safe side) it shows that Marlin wasn't uploaded at all. It is a the same height as before. It's a 22.2 mm difference so it is easy to see.


I have tried restarting the Arduino board before and after upload. 
I have tried unplugging the USB cable before and after upload.
I also tried two different USB ports.
The computer has been rebooted.
I have examined the Arduino editor's settings, so it uploads to the correct destination (COM3 in my case). It is as it should be. It, of course, reports "upload complete".


What can be the cause of this?
Are you sure that the firmware is not being uploaded?
You can debug this changing the STRING_VERSION on Configurations.h.
If the version is not being changed, I would suggest trying to use another computer to upload the firmware or even another board.