SyncUp app not working with watch

Same issue since yesterday 

Just bought watch today. Set up in store. By the time we got home, same app crash as everyone else. On the phone with outsourced customer service for over an hour. They had no idea others were experiencing the same thing. Went back to store, and they had no clue either. Not sure why neither of them can check the community board here, but we're returning the watch tomorrow.

Good to know I'm not the only one. Can't open the app since yesterday. It is definitely very frustrating to be paying for service and it not working. It be nice if they credit us the service missed.

Our watch has been dropping calls and not receiving texts for several weeks. We factory reset it last weekend (that didn't help) per a T-Mobile rep and opened the app to add grandparents back as contacts today, but app won't open and says, "All items core API failing." Spoke with a T-Mobile rep, who said this started today, and was told to check back in this thread for an update. It's very frustrating to pay for a device that doesn't even work. We got this for peace of mind when our child goes to a friend's house or has a sleepover, so they can contact us if something makes them uncomfortable or they want to come home. I am seriously considering moving to a different carrier (Verizon has the same watch, and it works WAY better on their network, check out the reviews). We've also been having problems with our phones working (not sending or receiving texts and phone calls). We spent HOURS on the phone the past couple of weeks with one rep saying they would send us a signal booster, and then when nothing showed up in the mail, and we called, that rep said they don't give out signal boosters. My kid's watch not working is the final straw for us. Get it together, T-Mobile! 

Also having issues with the app for the past 24hrs! The whole reason we got the watches is to be able to see where/what house in the neighborhood our girls are playing this summer.

Mine is also doing this. 

Same for me!I tried to uninstall it and it does the same thing.

Same for me

I am having the same problem with my kids watch/app. Started today.