There are two versions of Plans when working in Teams from what I can understand.
The first is a plan created for the Team as a whole, which I believe is based on the O365 Group created for the Team. This primary plan will be visible within the Planner Hub as standard. I believe this is the first Plan created for a Team.
If you create any subsequent plans against any other channel in that team you will have a Plan that you will not be able to fully see within the Planner hub.
You will be able to see any tasks assigned to you within the My Tasks section of the Planner hub.
An over view of the channel plan can only be seen within the Planner tab you created for this channel. This overview is limited to the tasks and buckets within that Plan, you won't see the donougt graph etc.
It is still a bit confusing I know, but I hope that the MS developers correct this in the short term.