You could try and clean the storage of your phone app. Maybe it helps???
Maybe you have connected the contacts from your dialer to a contacts app that looks like the native contacts app but this app that you're actually accessing from the dialer, doesn't have permission to see the contacts. A real long shot but not impossible. I don't if this sentence makes sense to you so to make it more simple. If you have two contacts apps in your app drawer, make sure to uninstall the one that isn't native. The Truecaller app is one example of a contacts app
If someone else jumps in here saying that they have this issue too, then we can investigate by logging your phone
