Second card in last six months, not sure what is causing it. First card still works fine in my wife's tablet. Any ideas?

Try cleaning the contacts of the SD card with a Q-Tip moistened with isopropyl alcohol first. If that doesn't work, then try the following tip from Tom's Hardware:

 

Lg G3 SD Card not recognized any more

 

I got a new Moto G 4th Generation about a month ago that would not read any SIM card, so I returned it to Amazon. The replacement worked fine. The Moto G has a poorly designed SIM card slot that does not always make contact with the card.

 

Hopefully, the problem that you are having with your phone is with the card or a software issue and not a design flaw with the phone. I tried several suggestions to make my first phone read a SIM card and had no luck.

Thanks, @Dino Nova! I'll give these tips a try.

Put a new card in with no added files, same problem. I'm guessing it's the phone.

Turned out the card reader on the phone was about to bite the dust, dang thing even deleted my playlists. Hated to, but ponied up for a new phone.