In version 0.39.12 I can't seem to get sorting to work at all. Pressing the top of the column for "Subject", "Size", or "Age" does nothing. Even tried highlighting multiple entries in the queue and it still does nothing.
Edit: Just noticed that it's actually sorting the articles inside each queue main entry. Didn't see it because they were all collapsed to a single line. I wonder if this could be improved to allow global sorting of the main queue entries also.