How did you get Samsung pay to work on O?
It's probably an incompatibility with the highest API for the Samsung Pay app being N.I'm have a pixel XL with a Samsung Galaxy gear S3. So I installed the Android O Beta and now I don't have Samsung Pay anymore on my watch.
I'm in this exact boat -- and I just had this thought. Searched the forums -- found this post. and that confirms it.
Going to revert to N and see if it works. Thanks for this!