It shouldn’t do this. You can go to Settings -> Phone -> Silence Unknown Callers, which will send callers not in your contacts to voicemail, but the silencer simply mutes audio. It still vibrates and receives calls. Or maybe there’s something I’m missing?

Well, it did do that. I checked, and that setting is off.

Almost like Apple products can have unintended bugs like disabling your alarm on OS update.

Easy now. I didn’t say it didn’t do it, I said it shouldn’t do it. You made it sound like you thought this was what was supposed to happen, and I just wanted to help you out.

Edit: Apologies if the last sentence in my first message seemed rude. Not my intention.

That's weird, that's not the case for me. Mine still goes through the length of ringing with the call on the screen.

You must have it on do not disturb. I exclusively keep my phone on silent (but within view) and have no problems answering calls because it pops up on the screen.

No, it wasn't on that at the times it happened.