I have an iPhone 6s with iOS 11.2.1. Just got a Vivoactive 3 and installed Garmin Connect Mobile, version 4.1.5, on the iPhone.
This is what is happening:
The app opens to the page where you select Create Account or Sign In.
After Sign In is selected, the Legal page opens, where you check the two boxes and hit Next.
After Next is selected, a page begins to load with the title "Sign In", and then the app closes.
No matter what else I try, I get the same result, once you get to the Sign In page, the app closes.
I have deleted the app and re-installed it.
I have searched the forum for a solution, but nothing I have found works.
If anyone has a solution for this problem, please advise.