Hi @Rogan ,
You will need some additional steps in your flow.
Let's assume that I want to update this task to "completed":

I will start by listing all tasks in my planner (unfortunately, there is no option to add filters in this action):

Then I will add a "Filter array" action, passing the "value" property from "List tasks" as "From", and the filter criteria (in this case, the task name), as "Filter Query". I'm hard coding the name of the task in this action, but you can also set it dynamically:

Finally, in the "Update a task" action, I will pass the "id" property from "Filter array" action (be careful to not assign the "id" from "List tasks", as it will result in updating all your planner tasks to complete):

After this step, you must notice that Power Automated included a "For each" loop. This is a default behavior, as technically your task to be updated is stored inside an array, which needs to be looped:

After running the flow, this is the result:

Note: I see that you are using the old designer for Power Automate. For this flow, I recommend you to keep using it, as in the new designer for Power Automate some bugs are expected in the "For each".
Let me know if it works for you or if you need any additional help!
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