Do Not Disturb mode ignores favorites and redirects them to voicemail

Since a few month I have the problem, that if I enable Do No Disturb mode every caller gets to my voicemail, even if the user is listed under my favorites. I also checked, that under Settings -> Do Not Disturb -> Allow Calls From -> Favorites is enabled. I was able to reproduce this problem on different iPhones with different Apple IDs (Already tried 6 different iPhones).

Here are the steps to reproduce the problem:

• Goto Settings.app -> Do Not Disturb
• Check that Allow Calls From: Favorites is set
• Disable Repeated Calls (so you can test it more than once every 3 minutes)

• Goto Phone.app -> Favorites
• Check that the caller is in your Favorites list

• Now enable Do not Disturb mode
• Lock you iPhone

• Call the iPhone from the other phone

Actual Result:

• Caller gets redirected to the voicemail box

Expected Result:

• The iPhone rings

Does anybody know how to fix this? I know a workaround would be to allow all callers in Do Not Disturb mode.

This bug is specially bad if you have a job where you have to be on standby.

I am on the latest iOS Version (12.1.4) but this problem exists now since a few month. I have also reported a radar: 46752611a few month ago, without any response yet.