Pedometer ++ is not on Apple Watch. It is available to install but is not. I press install from the list of available apps, press side button on iWatch and nothing. Does not install. Why?
Brand new iPhone 14 Max Pro.
Apple Watch Series 3, watchOS 8
With Series 3 watch you really ought to unpair or erase the watch completely then pair up as a "new watch" without restoring backup. You are very lucky it paired at all.
Best advice for problems with third party apps not written by Apple is to contact the developer
How to contact an app developer - Apple Support