Hmm, that's strange. What shows when a call is coming in? So you still see the number and not a contact, or is it entirely blank?
I'm having the same issue with my G4, and all it is showing is the number and no names on in coming and out going calls.
OMG, I just went through this at the exact same time you found the problem. It must have something to do with the software update they pushed down.
I, too, did factory reset--twice--with no luck. Man, I was bummed. I even did it a third time, this time from power off using the buttons on the phone. Still no go.
It finally occurred to me that in olden days, on a Samsung Galaxy S3, when I reset from power off using the phone buttons I would get a command-line-like screen that gave me some options. One of those options was to clear data and cache on the phone. V10 didn't give me that.
So I did the next best thing: I booted the phone and cleared the data and cache from the Call application. SUCCESS.
Settings, Apps. You'll see a list of apps, but the one you want isn't there. In the hamburger menu in the top right, pull it down and choose "Show system". Now when you scroll down that list, you'll find Call.
Choose Call, then press on the Storage item. Now you can clear data and clear cache.
There's also Call Management and Call Services. Do the same for them.
For grins, find the item Contacts and the item below it, Contacts Storage. Do the same for them. Clear data and clear cache.
Reboot your phone.
Let us know how this works out.
I actually found the solution also. After I factory reset everything, I would update or install apps that I know I used. Well I did not install Android System Webview and it worked. Everything was back to normal. Google Playstore aday later decided to update it for me and it went back to showing now contacts. So I go into the playstore and uninstall their latest update and again everything went back to normal. My contacts have now been restore. I also did not let google playstore auto-update this app anymore.
Jeeze, what a pain.
Well, thank you for sharing the solution, now I'll know what to tell anyone who has the same issue in future!