G'day Adam,
I know it sounds bizarre but it's the last chord, not the first that's the difference...
If you notice, in the last chord of the first slurred section, the tied note (stem up, Pos 6) is stated before the slur destination (stem down Pos2 -4,3)
The last chord in the second slurred section is the other way round, the tied note (stem up, Pos 6) is stated before the slur destination (stem down Pos2 -6,1)
!NoteWorthyComposerClip(2.0,Single)
|Rest|Dur:4th
|Chord|Dur:4th,Slur|Pos:-3,4|Opts:Stem=Down|Dur2:Half|Pos2:6^
|Chord|Dur:4th,Slur|Pos:-4,3|Opts:Stem=Down
|Chord|Dur:4th,Slur|Pos:6^|Opts:Stem=Up|Dur2:4th|Pos2:-5,2
|Bar
|Chord|Dur:4th|Pos:6|Opts:Stem=Up|Dur2:4th|Pos2:-4,3
|Rest|Dur:4th|Opts:Stem=Down
|Rest|Dur:Half|Opts:Stem=Down
|Bar
|Rest|Dur:4th
|Chord|Dur:4th,Slur|Pos:-3,4|Opts:Stem=Down|Dur2:Half|Pos2:6^
|Chord|Dur:4th,Slur|Pos:-4,3|Opts:Stem=Down
|Chord|Dur:4th,Slur|Pos:6^|Opts:Stem=Up|Dur2:4th|Pos2:-5,2
|Bar
|Chord|Dur:4th|Pos:-4,3|Opts:Stem=Down|Dur2:4th|Pos2:6
|Rest|Dur:4th|Opts:Stem=Down
|Rest|Dur:Half|Opts:Stem=Down
|Bar
|Rest|Dur:4th|Opts:Stem=Down
|Chord|Dur:4th,Slur|Pos:-5,2|Opts:Stem=Down|Dur2:Half|Pos2:6^
|Chord|Dur:4th,Slur|Pos:-6,1|Opts:Stem=Down
|Chord|Dur:4th,Slur|Pos:-7,0|Opts:Stem=Down|Dur2:4th|Pos2:6^
|Bar
|Chord|Dur:4th|Pos:-6,1|Opts:Stem=Down|Dur2:4th|Pos2:6
|Rest|Dur:4th|Opts:Stem=Down
|Rest|Dur:Half|Opts:Stem=Down
!NoteWorthyComposerClip-End
Do you see what I mean? Dunno if this is a useful quirk or if it should be fixed...