I lost trace of the open issues with ties and slurs, so bear for me if this is already known.
In this snippet
!NoteWorthyComposerClip(2.0,Single)
|Chord|Dur:4th,Dotted|Pos:n1^|Opts:Stem=Up,Tie=Upward|Dur2:4th,Dotted|Pos2:b0
|Chord|Dur:4th|Pos:1|Opts:Stem=Up,Tie=Upward|Dur2:4th|Pos2:-1
|Bar
|Chord|Dur:4th,Dotted|Pos:n0^|Opts:Stem=Up,Tie=Upward|Dur2:4th,Dotted|Pos2:-1
|Chord|Dur:4th|Pos:0|Opts:Stem=Up|Dur2:4th|Pos2:-2
|Bar
!NoteWorthyComposerClip-End
the tie is fine until the lower note is added, then, as you can see, the tie "slips down" looking like a slur for the lower note.
I don't see a problem with measure 1.
In measure 2, the tie does not "drop". It just seems that way because of the augmentation dot.
Perhaps measure 3 in my attachment is less likely to cause confusion.
Alfred's discussion of Ties is not much help. In its subsection: AVOID AUGMENTATION DOTS, the tie clearly starts just above the dot. But in: ADJUSTMENT OF TIES, the tie is much lower. Too low, I think.
IMO, an upward tie should not start below the top of the augmentation dot. A downward tie should not start above the bottom of the augmentation dot. In all cases, the tie must end at the same vertical coordinate as the tie start.
You're right: the tie don't move. It's the effect of the moved augmentation dot.
Anyway it surprised me.
I agree.