According to this document ( https://docs.microsoft.com/en-us/microsoftteams/platform/concepts/build-and-test/deep-links#deep-linking-to-a-chat ),
I attached this Anchor tag ( <a href="https://teams.microsoft.com/l/chat/0/0?users=XXXXXXXX@YYYY.co.jp"> ) on my developing Application
so that our customer can easily open and start Microsoft Teams chat with certain person from our application screen.
The problem is that
in using mobile device ( iPhone8, iOS 14.4.1 ) ,
if teams app has not launched yet,
the teams deep link only launch the teams app
but won't navigate to a chat screen with desired user.
( Instead, it just show the last screen before teams app were closed. )
※In contrast, if teams app has already launched, the teams deep link succeeds in taking user directly to a chat screen.
※When not using mobile ( = in PC ), the problem above won't happen.
I hope the problem to be solved.