Was Facetime broken on devices?

So I started experience this issue since last week. Before that this was working since I bought the device..

have appleid1 and iPad2 Wifi Only - 9.3.5

• this appleid1 is signed into iPad2 (using it for FaceTime Video and Audio)
  • issue - not receiving or seeing missed FaceTime calls while screen is locked (no passcode) and in sleep mode but I can receive calls on the home screen. I can also make facetime calls. if the screen is locked for 2 seconds then a facetime call can come in but anything beyond that the lock screen doesn't show any indicator of the FaceTime call.

Troubleshooting

• OS: after verifying the settings the issue still persisted so I ended up wiping and restoring it and setup the iPad2 as new again. Didn't restore settings from the backup.
• Network: I thought maybe the network was the issue so I used my wifi first which didn't work. Then I tethered my iPhone to the device. The issue still persists.
• Hardware: I even got another iPad 2 wifi wiped and restored 9.3.5 on that, logged into that iPad with the appleid above and it also had that issue. Not initially but after a few attempts the next day the same behavior.

Has FaceTime been broken by accident or on purpose? A little concerned..

Can anyone with an iPad 2 and 9.3.5 confirm this?