Patrick, that is exactly what my Mother's problem was. I saw your post after I made my comment, and had my mother go back in and edit the text back to the standard, and that completely fixed her problem. She had edited the text size to a larger size so that she can see the screen without her reading glasses. As soon as she put it back, it worked perfectly. Thank you!!!
Apple, this is an issue that needs to be fixed. Not everyone has perfect vision, and older people need to adjust the text sizes to help them see. My mother has an iPhone 6+ which is a little easier to see, but my father is still using an iPhone 4.