When you have task view set to sidebar, if you go to the inbox you'll see that the task you had opened overlaps in a strange way with the the sidebar that opens in the inbox when you click on notifications. So if you click on a notification, it tries to open the related task in the sidebar, but since you already have another task opened in the sidebar, it kind of remains in the background.
This makes a lot of confusion.
Since the task sidebar view and the task sidebar that opens when you click on a notification in the inbox are basically the same thing, they should probably act like they are one. So they shouldn't overlap one on top of the other but simply replace the content. Also the inbox should take into account the fact that you already have an opened sidebar with tasks and resize on the left column instead of laying in the background.
I hope I made myself clear :/