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

I caot notate below a low F below the bass clef, as the notes are gray. This is extremely aoying. 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 caot notate this unless I manually move the note.