New SSD not recognized by my Mac Mini 2012

Check the SATA cable connection on the logic board. It has a habit of not seating or popping loose when you install the antenna plate and black plastic cowling. Normally I add a thin piece of foam tape on top of the flat connector to help hold it in place.

FWIW I looked at those WD SSD’s, but I’ve had such good luck with PNY SSDs in the 2010 thru 2012 Mac Mini’s, that I stayed with PNY.

Could be a faulty WD SSD. To test it you will need to put it into a USB 2.5" enclosure or on a SATA to USB adapter and test it plugged into the Mac Mini or another computer. Also note, that you will need to partition and format any new drive, GUID Partition Map / Mac Extended (Journaled) before you can install macOS.

Popping loose is not a good sign! Either you damaged the cable or

not completely seating it in the socket.

Suggest looking for a replacement cable.

The constant heating and cooling will eventually loosen the tape.

Excellent point woodmeister50.

It also helps to reinstall the antenna grill and replace the 2 drive mounting screws before connecting the SATA cable to the logic board.

I will admit though, that I had a little trouble getting the OWC Data Doubler cable bent just right, in the 2011 Mac Mini that I use as a media server.

You’re welcome.