Just found out this hack and tried on my UT210E. Worked great!
Two observations:
1. By adding a 2nd feature (AC mV) in NCV mode, using the below 2-byte hack, you also add a 3rd feature (AC A 6000A) which seems silly to me. The $1D byte is really useful for the mV feature to work? Because all it does, is to enable the 3rd feature.
NCV, NCV mV
---------
9C: 00 02
AC: 00 1D
2. When I opened my unit, I noticed a QC fail. The R37 resistor was soldered only in one of the pads. Still worked tho, even after years of beatings around in the toolbag on many work fieldtrips.