I think you are not alone in having problems with that model... or so I have read on this forum. I can tell you that the 970 PROs (both) work fine in my system.
Me too. I have the 970 EVO Plus, and it wasn't working with the firmware installed as shipped.
I got the latest Samsung Firmware (2B2QEXM7) iso update from
here.
Side note: I was on Catalina, so the unetbooter wouldn't work there.
Using another computer with Mojave the unetbooter works and I made a USB to update the 970 EVO Plus.
I did not need to use Windows at all to do this.
Put the USB in, booted from it using F12, and it automatically detected the 970 EVO Plus and flashed it.
Another side note: After selecting
APFS, Encrypted for format in Disk Util, I had trouble installing to the drive. After I reluctantly selected
Mac Extended, Journaled when formatting the Drive, and it installed fine, but after install I looked at the drive and it is in fact
APFS after install. Still trying to figure out how that happened.
It does work perfectly with the latest firmware update.