That is a great question! Honestly, the mower may struggle with that bank even if you do manage to get it successfully mapped.

Was the lawn wet or damp at the time you were trying to map it? Traction is everything at that angle. I do know someone who had a similar issue and he installed spiked wheels that screw onto the outside of the existing wheels. This helped significantly when the lawn was soft, but it caused a large amount of vibration when the ground was dry.

One thing to keep in mind, however, is that adding spikes like that may invalidate your warranty, so it's a "use at your own risk" solution. He also wasn't navigating between zones on any hard surfaces; if you have to cross your stone or block driveway, those spikes would likely cause issues or damage there.

Regarding the specific maneuver of going up and reversing down without turning at the top boundary—the current software isn't really designed to handle boundaries that way. I'm sorry I can't be of more help, but that specific slope sounds like it is right at the edge of the mower's physical capabilities.