I think this is better here than in the general RNG thread, but I'm not entirely sure. I'd be happy to post there too if it's warranted.
I'm fairly new to RNGing; I've managed to successfully RNG a couple dozen Pokemon over the last few weeks, including an all-shiny rain team and several Keldeos from the WFC distribution that ended a few weeks back. My kids and I just went to get the Game Stop Meloetta, and I spent some time to RNG a Naive HP Ice (flawless w/Spe 30) one.
When I succeeded, the nature, IVs, and HP were all right; but the Characteristic that PPRNG suggested it should have didn't match the Characteristic that it actually has: The software suggested "Capable of taking hits", but it's actually "Mischievous". I'm pretty sure I had all of the settings right (it's been my experience that if I miss at all, I miss big; never before have I missed just the Characteristic while hitting the nature and IVs), so I'm not sure if this is a "bug" or merely some sort of fluke. But I wanted to report it, just in case it's meaningful to someone.