I know that's what it says in the datasheet
Do you not believe the datasheet? I've found arguing with either compiler error messages or hardware datasheets a useless activity, I always lose the argument. XD
Not sure what to say about your observations. Possible if I could see a real schematic and the electrical internals for your meters ( meters are current meters using internal series resistor to scale a given voltage to a given current), some explanation might present itself. And there are plenty of people around here smarter them me, so be patient if you want a root reason for your observations.
Lefty