I started seeing this before I upgraded to 7.2.2, but it is still here. I have no idea when it started exactly.
I see it when using reading pane. I click on a message and see it in the reading pane, then suddenly, and usually quickly, the focus jumps from the message to the Inbox. Leaving the reading pane empty. It will also do it when trying to select multiple message to move or delete. I'll do the CTRL-Click thing on 2 or 3 messages and suddenly nothing is selected.
This does not seem to happen outside of reading pane views.
Anyone have a clue? This is really quite maddening.