DW7.4, Ender5Plus, SKR E3 Turbo, DualZ Flag - G34 gives the same result at the end of each run.

[quarky42]

Description

This is my first time trying the DualZ Flag and the G34 Auto Align. It performs normally per various videos I've seen on youtube where it measured the left side, right side, and back 8 times. The first 3 times, it gave me 1:2=0.997mm. So I manually held one screw and shifted the other one. Then it repeatedly gave me the same result (better at 0.4 something mm). I shifted the screw again manually (holding one fixed and turning it) and this time it measured 0.04 when running G34. So, as far as I can tell G34 is just dancing back and forth around the value playing "Loves me" / "Loves me not". I watch the screen and I can see it updating values on the left and right, but it always ends up on the same value 1:2=Z from the previous run.

I am using the latest GitHub available DW7.4, touchscreen is updated with the TM3D_DWINCombinedScreens_V4.7z. The touchscreen is connected to the TFT port of the SKR E3 Turbo.

Steps to Reproduce

I run a GCODE file with just G34 in it on a freshly setup printer.

Expected behavior:
I'd like it to get more accurate when I run it. If I run it 1 time, it ought to get close. If I run it a second time, it ought to get closer. If I run it "n" times it should keep getting closer until it can't make the microadjustments based on physical / processing limitations.

With 800 steps per mm on z, 2mm pitch screws, that's only a half turn of the z screw. So each step is 0.00125mm.

Actual behavior:
I get the same value (1:2=Z) from the previous run of G34. During the run I see the measured z values fluctuate, but they are just jumping up and down by the same amounts back and forth, never getting closer to the ideal value.

I made a manual adjustment to one z screw while holding the other one fixed. When I reran G34 a couple times, it gave me a new value twice in a row. (0.4xx mm twice). I manually adjusted the screw again, and I got it down to 0.04mm on the next 2 runs. According to the Configuration_adv.h if it had gotten down to 0.02 on its own, it would have stopped, right? It never stopped on its own. It always ran 8 times.

Additional Information

My PlatformIO.ini:

[env:Ender5Plus_BLT_SKRT]
platform = ${common_LPC.platform}
extends  = common_LPC
board    = nxp_lpc1769
build_flags     = -DU8G_HAL_LINKS -IMarlin/src/HAL/LPC1768/include -IMarlin/src/HAL/LPC1768/u8g 
  -DMachineEnder5Plus -DABL_BLTOUCH -DSKRE3Turbo -DFORCE10SPRODISPLAY -DDualZ

ConfigurationFiles.zip

My changes to the config files are minimal. Some esteps / pid calibrations are applied. z steppers have been lowered from 850 to 730 because of the Dual Z.