Open ground question

Performed this inspection yesterday and left me scratching my head a bit. Why would a tester show an open ground when only one outlet of a 2 gang outlet is being used and then show that hot and neutral are reversed when the tester is in one outlet and the other outlet is in use? See photos… Thanks for any help!

Sounds like no ground and 1/2 normal 1/2 switched .

Thanks a ton.

I bet the plug in scent device was hitting your GFI button. Wouldn’t that throw it off?

Thats’s funny, very well could have been. The button has quite a bit of resistance though. Great observation. Thanks!