Rod has an iPhone 12 Pro Max, and when he tries to create a custom label for his three phone numbers, the labels disappear and are replaced by "home." The custom labels disappear. Leo says it could have to do with Syncing. If you're syncing to something that doesn't understand the custom labels feature, that could do it. Look into contacts, then accounts, and see what you're syncing with. See if it syncs with iCloud. If it's Outlook, it may be that Outlook doesn't support custom labels. Google Contacts doesn't mind. If you don't need to sync accounts, try turning that off and see if it fixes the problem. It could also be a bug, so you should report it to Apple.