Sorry, I don’t investigate issues with the watchOS betas until at least the 4th or 5th beta. I have wasted too much time in the past looking into bugs that Apple fix in a future beta.The buttons work but the view doesn't refresh when a button is pressed. If you go into the app switching view and back into the app then the view refreshes.
It isn't ideal, but obviously this is the first dev beta, so things like this are expected.
In addition this year I have completely rewritten the user interface and that new version should hopefully be released before watchOS 10, so there is no point investigating issues with the current version on watchOS 10.