Accidentals do not reflect key signature. Then naturals are lost.

[napsfan]

I've imported MusicXML for a piece in Ab (4 flats).  Yet, the notes show every single accidental as if the signature were in key of C, even though it is showing 4 flats.  And instead of showing a natural, it just shows the note without any accidental.  This is very wrong.

So then I transposed it to key of C, then back to Ab again.  (and I choose the option to adjust accidentals to keep the same notes)   That worked, mostly.   Now the notes that are flat in the key signature do not explicitly show the flat accidental.  That's good. 

EXCEPT -- now when returning back to Ab key signature, all the proper naturals are LOST.  So where there should be consecutive notes in my run showing E-natural, then E-flat, then other notes -- Both of the E's now show without ANY accidentals, so they both get played as Eb.  That is also very wrong.  They are NOT the same notes, they are supposed to be a half-step apart.  Why no NATURAL sign after transpose?  Ugghh.

Very frustrating that Crescendo seems not to be able to handle such a basic thing as key signature correctly.

I'm a newbie user.  Am I doing something wrong?