Planner sends emails for late tasks that have been completed

I am a team owner in Microsoft teams for my business. 

Microsoft Teams sends me the "You have late tasks!" email to tell me that completed tasks (that have been marked as completed). [See screenshot].

If I click on the link provided, it can't find the task it's talking about: [See photo]

And when I go into my Teams app, under tasks, it shows them as completed: [See photo]

How do I stop this from happening?

Thank you for your help.