Hi guys and gals!!! Okay, I think I have found a permanent fix! This has irritated me to know end! I tried all of the things mentioned before in this thread and they worked temporarily but was back to screwing up before nights end. Okay, here's what you need to do. (I'm using iphone 8 plus IOS 11.1.1)
**Make sure you're updated to the latest IOS FIRST**
1) Go to settings>Wallpaper
Change BOTH your lock screen and wallpaper to any Apple Live wallpaper. I believe this somehow updates the display drivers and/or installs them etc.
2) Restart your phone
3) You can then change your wallpaper and lock screen to whatever you want.
** I waited a 3 days to make sure this was a permanent fix before posting this fix and falsely getting everyone's hopes up** The Clock is back and I can see all of my notifications EVERY TIME!!!!
Good Luck! Let me know how it works for you!