Graph API: Plan and Task Created Successfully but Not Displayed in Planner

Question

I’m creating a Planner Plan, Bucket, and Task using the Microsoft Graph API within Power Automate. I have two questions:

The plan, bucket, and task are being created successfully (receiving HTTP 201 responses), but the plan does not appear in the Planner UI at planner.microsoft.com.

I’m attempting to assign the task to my own account using the same Graph API, following the official Microsoft documentation. However, I’m encountering a synchronization error during the assignment step.

https://learn.microsoft.com/en-us/graph/api/plannertask-update?view=graph-rest-1.0&tabs=http