You must select High End for the endstops in the configurator. If you don't it will do something silly like generate low end endstops for a delta. Which probably explains the crazy coordinates.
Make sure your M574 is configured for high end endstops.
https://duet3d.dozuki.com/Wiki/Gcode?revisionid=HEAD#Section_M574_Set_endstop_configuration
And yes, I've asked for the defaults for delta to be auto selected as high end.
