What it is: There is at least one SmartTask in your project plan that is dependent on the completion of many predecessor SmartTasks. In other words, there is a SmartTask that cannot be started until a series of other SmartTasks are completed.
Why it matters: A delay of even one of the predecessor SmartTasks can impact the task's start date. Depending on the completion of the many SmartTasks increases the probability that the successor task will be delayed. For example, in the scenario above, if five of the six tasks that are needed to hit the Launch milestone are complete but one is running a week behind, it is going to delay the Launch milestone by a week.
What's next: Consider breaking the bottleneck task into multiple tasks or milestones to mitigate this risk. If this is not possible, closely monitor status of all predecessor tasks to mitigate risk and ensure that the bottleneck task begins on time. This can be achieved by checking in regularly with task owners via chat or keeping a close eye on the tasks' percent complete updates.