My device is the RCA Viking Pro.
I have had some nether wart growing for a while but it would not grow. I thought it was just that I was not in the chunk radius enough so for the past few days I had just done stuff in and around my house. So after a while I got tired of waiting and destroyed what is the right side in the picture. They all droped the correct 2-4 pieces of wart. So I replanted it. In the picture the left is fully grown and should drop the full amount. But on the right I planted it right before taking the screenshot.