I have a gear S2 and I can use the app a few times, than it suddenly can't synch the faces anymore.
The 10 last faces are no problem to change, just the connection phone<=>watch seems to be the problem.
When I reinstall the app on my watch everything is working fine for a few times (sometimes even a few days, depending how much I change the watchface)
I tried using face-shuffle, but it never does, than it immidiatly starts acting like my phone isn't connected to the app.
I have a Samsung s8 phone.