I think it's really odd too. I have only owned Xperia phones almost all my life and this is the first time I stumble across this problem. I am not using a third-party phone app I just bought this phone a few days ago and it's using the stock application. I guess I'm going to have to restore the phone to factory defaults to see if that fixes the problem because I'm out of ideas.
I'll report back to let you know if that worked thank you all for your help.
Jay