LogAggregation might be on NOT_START state for two reasons:
(a) When an Application is submitted to Yarn, the initial state is NOT_START. If application fails very early, then the state remains NOT_START and the it is a final state
(b) While application is running the state is NOT_START. Just after it finishes, it makes a transition to RUNNING but for a (small) period of time remains to NOT_START.