Halo Infinite Weekly Challenges "not tracking progress" for players has been a problem since the surprise launch.
Players have experienced completing a weekly challenge but the game will still mark it as incomplete. Players can still earn experience for their season pass but an incomplete weekly challenge on your screen can be frustrating.
This means it's not you're fault, with its new release, developers are still working on fixing any necessary bugs and in the past, players have had trouble with the game when it released.
Halo Infinite Weekly Challenges Not Tracking Progress for Players
Players have tried uninstalling and re-installing the game, or restarting the game, console, or PC. If none of those solutions work, there's a reason why.
Halo Infinite Multiplayer is still in its beta stages and the full game with the campaign isn't set to release until Dec. 8. 2021, so it's no wonder the game still has bugs.
As of now, there are no official comments from 343 Industries about the bug. Since this is a developer-related bug, keep an eye out for updates on their support Twitter or the official Halo site for news.