Unbeamed notes do not have to have a stem direction while beamed notes do. Once they have a stem attribute, it has to be changed by force (audit note stems, etc).
!NoteWorthyComposerClip(2.0,Single)
|Clef|Type:Treble
|Note|Dur:8th|Pos:4
|Note|Dur:8th|Pos:3
|Note|Dur:8th|Pos:2
|Note|Dur:8th|Pos:1
|Note|Dur:8th|Pos:0
|Note|Dur:8th|Pos:-1
|Note|Dur:8th|Pos:-2
|Note|Dur:8th|Pos:-3
|Note|Dur:8th|Pos:-4
|Note|Dur:8th|Pos:-5
|Note|Dur:8th|Pos:-6
|Note|Dur:8th|Pos:-7
|Note|Dur:8th|Pos:-8
|Note|Dur:8th|Pos:-9
|Bar
|Note|Dur:8th|Pos:4|Opts:Stem=Down,Beam=First
|Note|Dur:8th|Pos:3|Opts:Stem=Down,Beam
|Note|Dur:8th|Pos:2|Opts:Stem=Down,Beam
|Note|Dur:8th|Pos:1|Opts:Stem=Down,Beam=End
|Note|Dur:8th|Pos:0|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-1|Opts:Stem=Up,Beam
|Note|Dur:8th|Pos:-2|Opts:Stem=Up,Beam
|Note|Dur:8th|Pos:-3|Opts:Stem=Up,Beam=End
|Note|Dur:8th|Pos:-4|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-5|Opts:Stem=Up,Beam
|Note|Dur:8th|Pos:-6|Opts:Stem=Up,Beam
|Note|Dur:8th|Pos:-7|Opts:Stem=Up,Beam=End
|Note|Dur:8th|Pos:-8|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-9|Opts:Stem=Up,Beam=End
!NoteWorthyComposerClip-End