This is for those who have older wallpaper and can't recover it
What I have done to remedy the situation, and I see that it persists:
- first of all I made a backup with iTunes
- after the backup finished, I went to the location C:\Users\YOURUSERNAME\AppData\Roaming\Apple Computer\MobileSync\Backup\something
- in that something I searched for b97b0c3bc8a6bb221d0849b450fbd92b5d06a301 which means Wallpaper (home screen). I copied the file to my desktop and renamed it to HomeBackground.cpbitmap
- also in that something I searched for 86736007d0166a18c646c567279b75093fc066fe which means Wallpaper (lock screen). I copied the file to my desktop and renamed it to LockBackground.cpbitmap
- then I went to https: // cpbitmap . github . io and converted the two cpbitmap files to JPG.
- uploaded them to my phone using iCloud
- deleted all the homescreens that already exists and made a new one using the pictures uploaded via iCloud.
Since then I haven't had any problems. The black screen hasn't appeared anymore and it's been almost 3 weeks since I did that.
I use DND all the time starting at 11PM and it ends automatically in the morning at 11AM.