Hi @slimmorrell,
Could you please share a screenshot of your flow's configuration?
I have made a test on my side and please take a try with the following workaround:
- Add a "When a task is assigned to me" trigger.
- Add a "Create a task" action, Subject field set to Title dynamic content of the trigger, Due Date field set to following formula:
formatDateTime(triggerBody()?['dueDateTime'],'yyyy-MM-dd')
Start Date field set to following formula:
formatDateTime(triggerBody()?['createdDateTime'],'yyyy-MM-dd')
- Add a "Do Until" action, click "Edit in advanced mode", type the following formula:
@equals(body('Create_a_task')?['Status'], 'Completed')
Within "Do Until" action, add a "Get task" action, Task Id field set to Id dynamic content of "Create a task action".
- Under "Do Until" action, add a "Update a task" action, Task Id field set to Id dynamic content of the trigger, Process field set to Completed.
Image reference:

Note: The "Do Until" aciton runs continuously until the Outlook task is completed.
The flow works successfully as below:
Best regards,
Kris