1. I had no problem installing and running same application to one of my watch.
2. Until recently it stopped installing with -12 error code saying “certificate in signature is not valid yet”
3. Certificate was made correctly considering i have been using it to install to a same device for a while.
4. When I installed on a different device with new cert, it installed fine.
5. Finally I tried factory resetting the watch. And it started installing fine with the same cert.

My question is, why is it happening?

And do I have to reset my watch everytime it happens?