I know that's unusual, but I met this case:
!NoteWorthyComposerClip(2.0,Single)
|Clef|Type:Bass
|Key|Signature:Bb,Eb
|Note|Dur:Half|Pos:-4^
|Bar|Style:Double
|Clef|Type:Bass
|Key|Signature:Bb,Eb,Ab
|Note|Dur:Half|Pos:-4|Opts:Stem=Down
!NoteWorthyComposerClip-End
Maybe we already saw it or something similar, but I'm unable to find the relevant discussion.
I'm not very smart in using the "find" of this newsgroup and my memory... bah! I'm somehow envious of Rick's one! :-)
A bug, but it is rare to insert a clef that is not a change of clef.
Yes indeed. It's just for "cosmetic" reasons.
In the other staves there is a true clef change.
...or a courtesy clef. But a courtesy clef would normally come at the end of a staff, where the tie would be broken anyway. I agree that this is a bug - but not a very serious one.
Bug or not, there's an easy workaround, Flurmy. Add a layered staff.
Change the first staff to
!NoteWorthyComposerClip(2.5,Single)
|Clef|Type:Bass
|Key|Signature:Bb,Eb|Tonic:B
|Note|Dur:Half|Pos:-4
|Bar|Style:Double
|Clef|Type:Bass
|Key|Signature:Bb,Eb,Ab|Tonic:E
|Note|Dur:Half|Pos:-4
!NoteWorthyComposerClip-End
and use this in the layered staff
!NoteWorthyComposerClip(2.5,Single)
|Clef|Type:Bass
|Key|Signature:Bb,Eb|Tonic:B
|Note|Dur:Half|Pos:-4^
|Bar|Style:Double
|Key|Signature:Bb,Eb,Ab|Tonic:E
|Note|Dur:Half|Pos:-4
!NoteWorthyComposerClip-End
Also note I changed the stem direction on your second note, but the workaround works whether or not you do that.