I've already submitted this as a bug, but for me it's a recurring problem. I'm posting it here to see if anyone else is having similar issues:

After selecting multiple ships and pressing the create fleet button, two issues occur:
* While the ships do appear to form a fleet, they do not immediately appear to have become a fleet in the display at the bottom of the screen. Only after I click twice on the fleet itself does the display show them as a fleet.
* The ships de-select (that is, the blue selection ring disappears from around the ships), although they still appear as unfleeted ships in the display below. This is also solved by clicking twice on the fleet.