As an end user I am also seeing this, none of the call blocking apps are able to ring my phone with incoming calls after screening unknown callers. For the app CallHero I get a silent push notification that I’m guessing should trigger CallKit to wake the app and ring the phone but that never happens.

I have been having this issue as a user after iOS 14.5 both robokiller app and callhero app are supposed to display the call notifications after screening the call to make sure its an actual person but my phone never rings, all I get is a silent notification saying to tap to open the app. strange thing is the developers of said app say they dont know of any issue like this as no one else is reporting this problem. I even did a factory reset on my phone and setup as new and same thing, im missing all my calls.

try going to privacy settings and then turn off the setting to allow apps to ask permission to track you, then turn on the option to allow apps to ask to track you. This worked for me and the call blocking section showed up right away. However I still am unable to get any apps to present a call screen and ring my phone after they screen a call. (robokiller/callhero)

After submitting version for review to Official app store and app was reviewed and approved. It took another 2 or so days before I could see the app in the app store or submit test flight builds.