Some have had issues when leveling the bed via the LCD screen. We've seen this happen when all of the thumbwheels under the bed are fully tightened and the extruder moves to probe at it's first position. You can loosen the first (front leftmost) thumbscrew and it can come all the way off without reaching the probe.

If you've seen this, try loosening the other two thumbwheels a bit. If they're tightened fully they can restrict the upward travel of the front left of the bed.