Fitbit Product Experts Alumni are retired members of the Fitbit Product Expert Program. Learn more
Although the S8+ was recently added to the list of supported devices it seems that a number of people are still having issues, particularly with notifications. Check out the main thread on this at:
https://community.fitbit.com/t5/Android-App/Samsung-Galaxy-S8-S8-Compatibility/m-p/1946855
Best Answer