Z drift over consecutive prints, resets on printer reset  

Z drift over consecutive prints, resets on printer reset

I am using a i3 MK2S, I have been using it without problems for several months now, but now a problem appeared.

My Z height keeps going up with every consecutive print. For example, I factory reset the printer and update the firmware and run all calibrations.
Then I run the V2Calibration for Z offset, I set it to the correct height around -0.540mm to -0.640mm. Right after I run the V2Calibration again to check the height, but now the nozzle is around 0.100mm to high, so I dial it down. Again, right after that I run the V2 Calibration again to see if its now correct, but again it is around 0.100mm to high, so again I dial it down. And so on and so forth, this happens with every consecutive print.

But now, something important. When I had done this a couple of times, I powered off the Printer and turned it on again right away. I then tried to print something and the first layer was way to low, it made a nasty mark in my bed! Turns out the correct height is now around -0.540mm to -0.640mm again, just like the first time I calibrated it (I have actually always been using -0.540mm all the time I wasn't having that problem before).

Seems to me like the Z height rises around 0.100mm every consecutive print, until it gets powered down.
I don't know what caused the Problem (maybe a firmware update?) but I since have tried everything, different firmwares new and old, all sorts of factory resets. The Pinda Probe isn't loose and the Pinda temperature calibration doesn't help either.

tl;dr
I uploaded a video of my problem with explanation: