AC electrical puzzlement

[Ole Anderson]

This sounds like it might be a case of reversed polarity.
They sell little plug ins that you use to check outlets for things like that.
https://www.gardnerbender.com/en/p/G...eptacle-Tester

Yes, this. Inexpensive and if you just plug it into a three prong outlet, will tell you if it is wired correctly, and if not, what the issue is.

[Tom M King]

You can get them in the box stores too.

https://www.homedepot.com/p/Klein-To...T210/206517824