Hello Kandium.
Thank you for using Apple Support Communities. It sounds like you're experiencing issues with monthly challenges not updating or syncing between your Apple Watch and iPhone. We can understand how this would be an issue. Allow us to investigate this issue and assist in any way we can. If you're noticing syncing issues, you can try to restart both your Apple Watch and iPhone to see if that helps:
Restart your iPhone - Apple Support
How to restart your Apple Watch - Apple Support
Additionally, if you do have any pending updates available for reach device, it would be best to install them. Keeping your devices fully updated can help resolve issues and also help with overall performance. Just in case, the resources below can guide you through the update process:
How to back up your iPhone, iPad, and iPod touch - Apple Support
Update your iPhone, iPad, or iPod touch - Apple Support
Update your Apple Watch - Apple Support
If these specific steps don't help, you might have to un-pair your Apple Watch from your iPhone and set it up again.
Unpair and erase your Apple Watch - Apple Support
Set up your Apple Watch - Apple Support
We hope this information is useful. Cheers.