Please review this for all firestick issues and guides, if the following hasn’t worked feel free to ask.
This should resolve most to all issues.
https://troypointinsider.com/t/resetting-your-firetv-os-and-firestick-guides/55887?u=tp-dracoo
There is an older guide in there for missing icons. The latest update for firetv fixed this supposedly. Check for updates.