Changing to key signature requiring the cancellation of accidentals doesn't show natural signs the first time (but does after)

Nightly 5225. Running Windows xp.
---------------
If you change from any key signature to another wich would require cancelling accidentals (Eg. 3#'s to 2 b's--> the 3#'s must be cancelled), the natural signs will only appear on the second time you drag-drop the signature:

1) Create a piano score from template. In the 2nd step, choose the key singature with 3 #.
2) Write F's on the 1st and 2nd bars. They will sounf as F# (fine!)
3) Drag-drop Bb major key signature on the 2nd bar.
--->The change of signature works (the F gets a # sign, if tou write more F's, they will be F-naturals)
---->The 2 b's of the new signature appear
--->HOWEVER, the 3 cancelling naturals of the previous signature don't appear.
4) Drag-drop a Bb major key signature on the 2nd bar AGAIN.
--->Now, the 3 natural signs appear (fine!)

If you change from any key signature with #'s or b's to C major, no new key signature will appear the 1st time.

Thank you!