Dear @Chris Bovio,
Thank you for posting your question in the Microsoft Q&A forum.
Based on your description, the Microsoft To Do app syncs correctly, but the taskbar/tray badge count does not update in real time. For example, after completing or rescheduling a task, the badge still shows the old count until the app is fully closed and reopened. You already tried restarting/resetting the app, reinstalling it, restarting Explorer, toggling taskbar badges, and confirming the app is updated, but the issue persists. You wonder this is a known Windows notification badge issue or a bug with Microsoft To Do.
For better understanding your situation, could you please provide some more information as:
Which type of account are you using (personal account or business account)?
Does the issue occur on multiple devices or only this PC?
Does the issue happen on all task lists or only “My Day”/“Planned” tasks?
Are badges from other apps (Outlook, Teams, Mail, etc.) updating normally?
Please understand that the more information you provide, the more effectively I can support you.
Looking forward to your update.