Can’t make call to specific number from family member Apple Watch Ultra 2

I got a watch phone for my preteen. Since my service provider is AT&T, I purchased an Apple Watch Ultra 2, which has its own mobile number and can make and receive calls and texts. The problem…after pairing and setting up the watch through my iPhone 15, I tested the watch and found that I couldn't make a call to my number only. All the other contacts on the watch were fine, but I noticed the phone icon on my contact was the only one grayed out. The fix…on the watch, I had to manually add myself as a new contact (using a different name or nickname). I spent a collective 6 hours troubleshooting with Apple and AT&T service techs. They weren’t exactly sure of the cause but said my imported contact info was probably associating with my Apple ID profile, which of course contains my mobile number and probably confused the watch.