[Q] No display when receiving calls?!

I have the Z3 compact and recently found when receiving calls my screen stays blank and does not display anything, notifcation led flashes and vibrates, as I cannot see who is calling I find I am having to press the power button to cut them off to see who it is in the notification bar to call back.
Any help would be great as been through settings, restarted, sim out, etc and still no change!?!