printKeyCancellation not working as expected

[SK]

Hello,

I would like to be able to change key signatures without ANY hints for educational purposes. For this I use Staff.printKeyCancellation set to false, together with the visibility options for key signatures. It works fine for most keys, but when changing to a key without any accidentals such as c major, the natural signs are shown and tell the student where there have been accidentals before.

Any help would be very appreciated.

keycancellation.ly
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