I'm not sure if you can see from this image (I have increased the transparency of the background layer to try and help demonstrate the issue), but when I add new questions, the 4th selection circle has a white background colour - whiter than the other 3.
Can you see this? Has anyone come across this before? I would maybe understand if this was the correct answer, but bizarrely it is not! It is happening on many if not all of my questions - any suggestions would be appreciated.