My app was working fine and has many downloads but suddenly I started getting many emails from users who can't get the install to work. I tried to install on one of my own watches and it's doing the same thing. You press install, press accept on the permissions, the button shows the installing swirly and then the button goes back to install.
I had been telling the users that Garmin support will have to help as I can't control installation or payment issues but when I tried following my advice, the support person told me to contact the developer.