Can not add Apple Watch 3 to T-Mobile Account

[underattack]

I had the watch working with Verizon, but just moved to T-Mobile. When I try to add the watch to T-Mobile via the iPhone Watch app, it asks me to the last for digits of my SSN, and then it just displays a 'Please wait' message and nothing happens (it eventually disappears). I added the "Digits" feature to the phone via the T-Mobile website. Has anybody else seen this happen? Is the watch still linked to "Verizon" (I since upgraded to WatchOS 4.0.1. Also removed the old carrier from the watch, or at least I think I did what it takes. The watch displays "No Sim" when I pull up the cellular settings on the watch). Or is this standard behaviour for T-Mobile?

 

[underattack]

Figured it out. I had to unpair the watch from the phone, the. Set it up as a new watch again. During the setup, I enabled lte and it worked like a charm