Every time I try and set this in OB software or even load up file containing all the GRBL settings it always reverts back to ZERO. What gives?
No, its not disabled. If you have enabled it and look at the console log it will show that $13=1. I think its just bug in the UI. Might have something to do with why that select looks different than the others as well. Peter will know. Peter, if you inspect the select, it does show value=1. UI just isnt displaying it correctly.
It should be Disabled, we expect Grbl to report in mm, and handle Inch conversions ourselves. Do not set it to Inch.
Yes, but click the Inch mode tab in CONTROL above the DROs. Leave the one in Grbl Settings alone. Grbl should reports in mm to CONTROL: CONTROL handles the conversion for you. PS: Inch mode was the default, if you see mm's you clicked on mm-mode at some point