I raised this in the 'HDR' thread a couple of days ago. For a couple of my recent projects, when I attempt to close MEP 2016 Premium by my usual method using the top right 'x' icon, it fails. Instead it empties all sections of the MEP window and waits.
Clicking 'x' again produces the familiar message:
So I click Don't save and all is well.
Strangely, using the alternative File > Exit method proceeds as normal, i.e. immediately closing MEP.
Anyone seen similar, or have any suggestions as to likely cause please?