I had some issues with sensorless homing when I first tried to implement it on my RatRig V-Core 3. I was determined not to install end-stops on this build, as I had them on my other printers and I just wanted to use all of the features my TMC drivers allowed me to.

I found that the current settings were just not spot-on for my build, and I adjusted them slightly. The following code was modified in the "sensorless-homing-tmc2209.cfg" found in the main config directory. Give it a try, and let me know if it helped you out.

The latest RatOS configuration in GitHub would simply not work at all for me, and I had to revert to the old config you see below.

# WARNING. DO NOT EDIT THIS FILE.
# To override settings from this file, you can copy and paste the relevant
# sections into your printer.cfg and change it there.

# BEWARE, this doesn't work if you've bent the DIAG pins on your x / y steppers.

[stepper_x]
endstop_pin: tmc2209_stepper_x:virtual_endstop
position_min: -12
position_endstop: -12

[stepper_y]
endstop_pin: tmc2209_stepper_y:virtual_endstop
position_min: -12
position_endstop: -5

[tmc2209 stepper_x]
diag_pin: x_diag_pin
driver_SGTHRS: 70 # Stall guard threshold, this is your X sensitivity, to adjust, copy this section and override it in printer.cfg.

[tmc2209 stepper_y]
diag_pin: y_diag_pin
driver_SGTHRS: 70 # Stall guard threshold, this is your Y sensitivity, to adjust, copy this section and override it in printer.cfg.

[homing_override]
set_position_z: 5
gcode:
    M400                  # Wait for moves to finish
    G90                   # Absolute positioning
    G0 Z10 F600           # Hop Z-Axis
    M204 S1000            # Set homing acceleration (important!)

    # Home Y
    SET_TMC_CURRENT STEPPER=stepper_x CURRENT=0.6 HOLDCURRENT=0.6
    SET_TMC_CURRENT STEPPER=stepper_y CURRENT=0.6 HOLDCURRENT=0.6
    G28 Y
    G0 Y{printer.toolhead.axis_maximum.y / 2} F9000

    # Home X
    SET_TMC_CURRENT STEPPER=stepper_x CURRENT=0.5 HOLDCURRENT=0.5
    SET_TMC_CURRENT STEPPER=stepper_y CURRENT=0.5 HOLDCURRENT=0.5
    G28 X

    G0 X{printer.toolhead.axis_maximum.x / 2} F9000
 
    # Restore current
    SET_TMC_CURRENT STEPPER=stepper_x CURRENT={printer.configfile.config["tmc2209 stepper_x"].run_current} HOLDCURRENT={printer.configfile.config["tmc2209 stepper_x"].hold_current}
    SET_TMC_CURRENT STEPPER=stepper_y CURRENT={printer.configfile.config["tmc2209 stepper_y"].run_current} HOLDCURRENT={printer.configfile.config["tmc2209 stepper_y"].hold_current}

	G0 X{printer.toolhead.axis_maximum.x / 2} Y{printer.toolhead.axis_maximum.y / 2} F3000
	
    # Rehome Z
    G28 Z
    
    # Safe Z
    G0 Z10 F600