Noteworthy

2. Make sure the key signature is in place. If it's C, insert that. (type K,C, enter)

Ah, so that explains why transposing from C to another key in Noteworthy goes pear-shaped.

Thanks for that - seems a bit counter-intuitive (having to insert a blank key signature field), but I guess it can't update the field unless there's a field there to update ...