Hi @Dina King ,
Welcome to our forum!
Looks like your issue is related to Microsoft To Do and Microsoft Planner. Please kindly understand that Outlook tag here mainly focus on the general issues about Outlook desktop client. Based on my research, i found that to see the tasks between Microsoft To Do and Microsoft Planner, you need to enable the below option in Microsoft To Do:
1.In the upper right corner, choose
Settings, then To Do Settings.
2.In Settings, scroll down to the Smart lists section and make sure that Assigned to you is turned On.
3.Then, under Connected apps, for Planner, choose On.
More information: See Planner tasks in Microsoft To Do.
Hope to help you! If it doesn't help, i'm afraid that you need post your case in dedicated forum for Microsoft Planner for more professional advice.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.