I have recently finally took the plunge and got the iPhone 17 pro max, I've noticed a few times that on the current 26.3, that notifications are not coming through. It doesn't matter whether the phone is on vibrate or silent. I made a call the other day and it didn't get answered. I put the phone in my pocket, went to the bathroom and when I was done I saw 2 missed calls from that contact. I never felt a vibration or heard anything and my phone was not on silent.