Settings: Typing, then blank screen
I am typing on FB or email and my screen will switch to a blank one with only a digital clock showing and a phrase that says updating photos. This has been happening for over a week now.
iMac, iOS 10, iOS 10.13.6
Try a safe boot.
Shutdown your machine. Hold down the shift key. Poweron. The boot up will take longer than normal because the filesystem on the startup drive is being checked and repaired as needed. All about safe mode including what features and apps safe boot leaves out.