ATT Selling Apple Watches But Cannot Set Up Cellular

Anyone experience this problem and found a solution? New apple watch ultra 2, successfully paired with iPhone, but cannot set up cellular. The ATT store could not set it up, even with tech support over the phone. Was told it could be a "back end connection problem" and to either keep trying or return the apple watch. Using the watch app on iphone to setup cellular for the watch repeatedly results in error message "Oops, that wasn't supposed to happen. Give us a minute and we'll get it fixed so you can try again (EDS0057).

Was in the ATT store for 4 hours while the store, on the phone with ATT tech support, tried multiple solutions. They exchanged the apple watch ultra 2 for another one, successfully paired again, but still could not set up cellular. Confirmed with tech support that it's not an issue with eSim, or the apple watch, or my ATT account. Walked out of the store with the watch and tried again today and still same problem. About to give up but really wanted to get an apple watch.