G29 Auto bed leveling extreme squish (2 replies)

With a newly installed z induction probe, I can use auto-bed leveling (ABL), yay!

BUT, I have an extreme case of z-layer squish because of it. In the first 10mm wihere ABL is compensating, my 10mm hight is coming out as 6.56mm. That is 3.44mm of squish!

Here is a photo [attachment 117692 ScreenShot2021-02-14at8.30.58AM.png]

That 3.44mm of lost height is a number suspiciouly close to what is in the bed leveling matrix below.

Loaded /Users/k/Desktop/PI3MK3M_xyzCalibration_cube.gcode, 12834 lines
1.33m of filament used in this print
The print goes:
- from 92.70 mm to 112.30 mm in X and is 19.60 mm wide
- from 107.70 mm to 127.30 mm in Y and is 19.60 mm deep
- from 0.00 mm to 20.00 mm in Z and is 20.00 mm high
Estimated duration: 100 layers, 0:16:02
Print started at: 20:54:48
Selected home phase 896 too close to endstop trigger phase 952. Pick a different phase for 89
Preheating
Wait for bed heating...
Wait for bed heating...
Wait for bed heating...
Bilinear Leveling Grid:
      0      1      2
 0 +3.705 +3.425 +3.560
 1 +3.307 +3.450 +3.557
 2 +3.305 +3.397 +3.425
start

This cube is done with the latest bugfix-2.0.x branch.

Should I be adding the smallest number below to my configuration with a M206 Z-3.305?

And/or should I be adjusting my Z-probe offset height (currenly below)

echo:; Z-Probe Offset (mm):
echo:  M851 X55.00 Y19.00 Z-0.60

In my configuration, related to zprobe offset, I already have

#define NOZZLE_TO_PROBE_OFFSET { 55, 19, -1.11 }

FYI: For this thing to even print like this, I had to reduce the filament flow rate to 50%!
PS: The cube in the photo isn't curved, curves are thanks to my janky-cam macro lenz.