That's great to hear!Just got the new beta and the action button is working flawlessly now, pause/resume, intervals, etc. Nice work!!
However I am still worried about the problem with watchOS 9.1. It seems to happen after rebooting the watch, so it's best to avoid that. If you do reboot it then please let me know if it breaks the action button functionality. If so then reinstalling the watch app seems to fix it.
It would also be interesting to know if anyone on the watchOS 9.2 beta has the same problem.
I can't release to the App Store with such a problem so I need to fix it somehow. I just hope that it is something that I am doing wrong, and that it isn't a watchOS issue that I can't work around.