I fixed mine by opening Samsung Pay, and allowing it to change the default payment provider, then going back into Google Pay and setting that back to be the default payment provider. I didn't add any etc to Samsung Pay or anything, just came striaight out of it.
I didn't need to clear the Play Services Cached etc either.
Hope that helps.
Well, Android Pay now works without me changing anything to fix it. Samsung replied to tell me that the Beta can cause issues. However, my phone told me an update was available so I downloaded it. I'm not aware that beta updates are pushed through in this way.
after 3 days it will not work again (can be)
tap to Google Pay and hold
in the meny choose ABOUT APPLICATION
tap to Battery
and turn ON background activity
It's disappointing results Samsung needs to focus on user experience rather than its phone spec , you can't use Google pay on gear S3 , now after the UI2 update you can't even use it on S10 I want a full refund