BTW, never a good idea to say Corona is the "latest" - we can't tell from that whether you mean "latest official release", or "latest daily build", and there's also the danger in both cases that you think you have the latest but there is in fact another version out... so please always give what version it is, like Corona 6 HF 1, or Corona Daily Build March 5th. That way there is no possible confusion or error on either side :) Thanks!
Meantime, have never heard of this issue myself. What was the CPU usage at the time? You say it finished rendering, but stats were still updating (they would only update if it had not finished rendering and was still calculating) so I am not sure what is meant there - which stats were updating still, and what made you think the render was finished?
Just to check, you don't have "Lock 3ds Max during render" enabled in the System Settings? (It is disabled by default - if enabled, it would make Max unresponsive to any clicks etc. under rendering had indeed finished).