In sim/axis, which is an inch config, I load nc_files/systems.ngc (which does not contain either G20 or G21) and run it. In master, it draws labels an inch or two wide, because the default units are inches, as expected.
In state-tags-master, it draws tiny labels a mm or two wide. If I go to MDI and enter G20 and then run the program again, it STILL runs in mm mode. Both the mm default and the MDI G20 not working are incorrect.
(If I add G20 to the gcode, it runs in inch mode as expected.)
Oops I meant by the second paragraph's "it draws" that while the preview shows in inches (correctly), when running the program you get mm motion, which does not match the preview.