I did just worked around this by first creating the task in Planner, then adding another Flow action immediately after the Planner Task Create to Update Task Details. It accepts the Task ID from the create action output. However, this seems like a bit of a hack. Being able to fill in any/all of the available Planner task fields on create would be more logical.
I'd love to be able to add/edit the Links from the Planner task - add a link back to the orginial SharePoint task, for example.
It would be useful if you could enter data into the planner description field (and maybe even the attachment field) as part of a flow. Including passing a description over from a Dynamics 365 entity.
I cannot reccomend the above comment enough. It feels like a natural step - not sure why it's not possible. Is there any way to use the action, "Get Task Details"? Holding my breath that this one comes through...
We were looking to allow a Flow to take info from sharepoint and capture it in the description of the planner task. The field was not available and we would like it to be so that we can have more information placed in our planner solution.