You already have my profile that exhibits this problem. It was the same with the 3804 build.
It's not about restarting Mach, it's when you exit config and then re-enable the drives without exiting Mach.
If you change say the backlash compensation value when you're in Metric, then exit, enable the drive and step 1mm, it will step 1". It does it for other things too, but I know this definitely is wrong because I've adjusted the backlash values in the last couple of days and it happened then.
I'm only using Metric, never Imperial. That's what makes it dangerous, you don't expect it to change from Metric when you exit the config. It really shouldn't do that. There must be something in the code that defaults to Imperial somewhere on exit, or when you edit the values.