Bug in exporting MusicXML

New to MuseScore, and blown away by this incredible software.

But I think I've found a bug. When I have MuseScore in Concert Pitch and export my score to a MusicXML file and then import it back into MuseScore, everything is done correctly except for the key signatures at the beginning of each page, which are the same as they were in Concert Pitch. In other words, if my piece is in Bb, every instrument shows two flats as its key signature, but the notation is correct for the transposed key signature. Plays perfectly so it must be only the visual representation that is off, not the internal key signatures. Now I know I should have switched Concert Pitch off before exporting, but it would be good for MuseScore to handle it correctly regardless. (I later exported it with Concert Pitch off, and it worked perfectly.)