Niko on 13 Sep, 2018 09:26 AM
I’m very happy to hear that you like the app!
There is a rule about nested tasks: Parent tasks can't have their own timings.
So the “Add Subtask” item is greyed out when the task you are trying to add the subtask to already has timings associated with it.
You could add a new “parent task” and make both your existing task and the new task subtasks of it (using drag & drop).