Sync-Up Kids Wach not working in Vancouver, BC

Does anyone know if the Sync-up Kids watch works in Vancouver, BC? It supposed to work. I drove there from WA state on 2/18/2024 and as soon as I cross the border to Canada, the watch stop connecting to the mobile network. It showed 5 signal bars with a line across. My phone in the other hand showed it is connected to LTE with 5 bars.  We then went to Whistler and still it never connected to the network throughout our trip (1 week). Then when we came back and crossed the border into US, it connected right after the border.  

I debugged the problem with T-Mobile support for more than 3hrs while in Canada. After several resets and restarts of the phone and the back-end systems, could not resolve it. 

Has anyone else seen this issue? Would be a bad device? I just purchased this watch about couple of months ago. I remember the previous Sync-up kids watch I had worked in Canada.