My suggestion would be to turn off all bed leveling. And get the Z_PROBE_OFFSET_FROM_EXTRUDER number correct so you can home in the center of the bed, and print a small object there. Perhaps a 20mm calibration cube.
When you can do that (with no bed leveling turned on or built into the firmware), then you are ready to turn on UBL and follow those steps in the 'Cheat Sheet'. If you do this, you have have a 95% chance of getting a fully qualified, fine tuned mesh the first time.
When you can do that (with no bed leveling turned on or built into the firmware), then you are ready to turn on UBL and follow those steps in the 'Cheat Sheet'. If you do this, you have have a 95% chance of getting a fully qualified, fine tuned mesh the first time.