Blocked contacts

Can you click on any of the other menu items, such as Call Blocking & Identification? Do you have any call-blocking apps installed that you can see there? If you do, I'd suggest removing them. Are you by any chance sharing an Apple ID? Not sure that that should make a difference but, if you are sharing an Apple ID with another phone, I'd try checking to see if you can see the list there. That might tell us if the problem is with the data itself.

The next thing to do would be to back up your phone and then restore it from the backup, preferably using a computer as that way, you'll get a fresh copy of iOS which doesn't happen if you do the procedure using iCloud. I would be inclined to back the phone up, restore it to factory settings, and test it. If it's working fine, restore your backup. Test again. If it works in factory state and not when you restore your backup, you'll know that you have an issue with the data on your phone.

• Restart the device. That's it.

Why obviously? Restarting the phone frequently fixes little glitches. And, no one here would know what troubleshooting steps you've already done unless you tell us.

So, what other troubleshooting steps have you taken? What model iPhone are you using? Does it have the most up-to-date version of iOS?

If it's happening on both phones that share an Apple ID, which means they share the blocked contacts list, then the problem is most likely with the data. There may be some corruption that is causing the problem. Unfortunately, unless you can get to that list, I don't know of any way of deleting just that information. It's also within the realm of possibility that it's an issue with less obvious data but, I don't know that there's any way to determine that.

Some other random suggestions, in no particular order. Try going to Settings>Mail>Accounts and removing all of your accounts. As long as you know your passwords, it should only take a minute or two to add them back. Test. If you can get to the blocked contact list, delete everything. Also, check Settings>ScreenTime to see if you have any restrictions set. I can't think of any that would cause this but.... Force quit the Settings app if you haven't already.

Can you access the list through the TrueCaller app if you re-install it. If so, delete all the blocked contacts and see if that gets you in. I've never heard anything bad about the app but it's possible it did something.