Amazon Basics charger cable "not certified"?

A week ago, I bought an Amazon Basics charger cable for my iPhone 6s (The cable is MFi certified). It was working perfectly, until about 5 days ago, when it suddenly decided to stop working. Whenever I plug it in, this message appears: "This cable or accessory is not certified and may not work reliably." The phone charges with any official apple cable, but not at all with any non-official cable. I have tried the following:

-Cleaning out the charger port VERY THOROUGHLY (toothpick, compressed air, etc.)

-Restarting my phone

-Unplugging and plugging back in repeatedly

-Restoring my phone to factory default.

Any suggestions?