Notes turn gray at low E on the bass staff. Why?

I cannot notate below a low F below the bass clef, as the notes are gray.  This is extremely annoying.  Why?

I asked this question more than a year ago when trying out Notion 5, moving to Notion 6.

Eg., A bassoon can play beyond a low F, down to a low Bb, but cannot notate this unless I manually move the note.

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