I found several outlets in one room that tested as almost having an open ground (LED on right faintly lit up – see pic), in a house with grounded wiring, and other outlets tested as properly grounded. The VOM, read 119V from H-N (OK), but only 23V from H to G, and 11V from H-N.
So the outlet appeared to be working for 2-prong purposes just fine, but appeared to be weakly grounded. I did a search and couldn’t find any threads on this sort of thing.
First explanation that comes to mind is a poor grounding connection in the circuit, with excessive resistance. The room did appear to have been converted from 2 rooms to one big room, so amateur wiring appeared likely, with probably junctions in light fixture and/or switch enclosures. What’s going on here?