[grblHAL/STM32F4xx Issue#140] SKR 2.0 with TMC2209 – sensorless homing auto-align

I have a low rider CNC (X, Y, Z, Y2, Z2).

When homing my Z axis, the Z2 channel does not stop. If I apply force to the Z side it stops immediately. If I hold the Z2 side it will skip steps until the auto-align limits are reached.

The Y and Y2 axes auto-align beautifully.

I have jumpered the Z2 (E1M/M4) DIAG pin over to the PWRDET pin 3 (PC15) as referenced in the _map.h file for the board.
I have swapped motor connectors Z<->Z2.
I have swapped driver chips Z<->Z2.
I have changed jumper cables.
I don’t have a scope but I could probably find one.

Any trouble shooting ideas?

Config:
> $$
$0=10.0
$1=255
$2=0
$3=7
$4=7
$5=0
$6=1
$8=2
$9=1
$10=4095
$11=0.010
$12=0.002
$13=0
$14=70
$15=0
$16=0
$17=0
$18=4
$19=0
$20=0
$21=1
$22=235
$23=3
$24=25.0
$25=500.0
$26=250
$27=5.000
$28=0.100
$29=0.0
$30=1000.000
$31=0.000
$32=0
$33=5000.0
$34=0.0
$35=0.0
$36=100.0
$37=0
$39=1
$40=0
$43=1
$44=4
$45=3
$46=0
$62=0
$63=3
$64=0
$65=0
$100=100.000
$101=100.000
$102=400.000
$110=500.000
$111=500.000
$112=500.000
$120=10.000
$121=10.000
$122=10.000
$130=200.000
$131=200.000
$132=200.000
$140=1700
$141=1700
$142=1700
$150=16
$151=16
$152=16
$170=0.000
$171=0.000
$172=0.000
$180=25.0
$181=25.0
$182=25.0
$190=500.0
$191=500.0
$192=500.0
$200=22.0
$201=22.0
$202=80.0
$210=50
$211=50
$212=50
$220=22.0
$221=22.0
$222=80.0
$338=7
$339=7
$341=0
$342=30.0
$343=25.0
$344=200.0
$345=200.0
$346=1
$347=50.0
$348=0.000
$349=250.000
$384=0
$398=35
$481=0
$484=1

Running from latest available commit (51e5e4f) with a few SDIO (thanks for that, btw!) related tweaks.

Submodules:
> ‘bluetooth’ at 07580ce
‘eeprom’ at fd157b3
’embroidery’ at 677436e
‘encoder’ at 59fd295
‘fans’ at 1a45424
‘grbl’ at 43691fc
‘keypad’ at 5402ab3
‘laser’ at 7ea8a5b
‘lwip’ at 76fec2a
‘motors’ at 11c937c
‘networking’ at 988ebc7
‘odometer’ at 689cca5
‘sdcard’ at 18c528d
‘spindle’ at 7d6929e
‘trinamic’ at 6231628