Is this specific for D4.3 and perhaps fixed in D5?
Notice the extra gap at 3rd note. Even more noticeable when you change the tie design;
where the vertical shift also can be seen.
Quite annoying from a pro program. Hopefully fixed (or will be fixed) and it’s my fault for not upgrading…
Are you in galley view? I haven’t noticed anything similar.
Does it print that way, or is this just a rounding error due to the resolution on the monitor screen?
I tried this in Dorico 4 and Dorico 5. It behaved the same in both.
In Page view, I input 8 A’s and slowly extended the tie one note at a time, observing closely during the process. After tying the first two notes, I noticed that the right-hand end of the previous tie moved slightly to the left each time a tie was added to the tie chain, thus increasing the gap. The gap between the end of the first tie and the start of the second tie remained unchanged. The phenomenon only occurred from the third tie onwards. If a note preceding the first note was added to the tie chain, the different size gaps moved to the left so that the smaller gap was only between the first and second notes in the tie chain. One other thing which I observed when doing this is that the left-hand end of the original first tie also moves when it becomes the second tie (I hope that makes sense).
I tried all the above in other time signatures as well - the behaviour was the same.
When exporting to PDF, the difference in gap size is present in the PDF.
@StevenJones01 I see the exact same thing described here by the OP and you in Dorico 5.0.20, Windows 11 Insider Preview.
It’s a small error, repeatable and deterministic. But engraving is all about very fine details, and the eye/brain, such an accurate system, picks up spacing diffs like this very easily.
The team on the forum does not like us calling things bugs, but this is a defect or at the very least an infelicity and should go on the (infinite 
) list of items to be corrected.
I am critically aware that ties and slurs are an incredibly hard area in engraving engines from my experiences with Lilypond. Not simple.
Eh? The team have acknowledged, and then fixed, hundreds of bugs over the last 5 years.
But something is only a bug when it’s not what the team intended. If they deliberately designed something, which you disagree with: that’s not a bug.
(I’m not suggesting that this is the case here – although … the best hand engraving inevitably showed small variations of this kind. Perhaps this is ‘Engraving Humanization™’ !! 
)
@StevenJones01 Thank you for verifying this.
Furthermore, the arc setting function seems incorrect to me.
gives me
but
gives me
The image in the setting shows(?) that the end points are fixed, yet they move. A bug? I think the setting of 1/4 is too small when printing and changing to 1/2 gives a too large distance.
@Andro I agree 100%. It’s all about the fine details. It’s remarkable that Sibelius produce (for this case and similar cases at least) better ties by default. The list of “things to be fixed in Engrave mode” is getting longer and longer which makes Dorico for me (and my kind of music) a less interesting option. Too many post-edits.
What’s happening here is that Dorico is not offsetting the right-hand end of the first tie in the tie chain. It is indeed a little bug and we’ll make sure it gets fixed in a future update.
Does this also fix the vertical shift and the strange behaviour of the arc height setting where the endpoints move too?
In addition it would be good if the middle of the arc is placed right in the middle of a space when it is “close” to the middle so it is not “almost in the middle” of the space.
Dorico has to balance the endpoint position with the arc of the tie, so it is the expected behaviour that the endpoints can move as well as the arc of the tie being adjusted.
OK I see, but it results in a “Catch 22” situation. With endpoints close to the note head the tie goes too close to the line, and with increased setting for distance, the endpoints move away from notes. Could an improved setting perhaps be made so a default/automatic arc can be made to avoid tedious tuning in Engrave mode?
I do not see this problem in either 3.5 or 4.0. I think that is because long ago I set
Engraving Options > Ties > Horizontal Endpoint Positioning > Advanced Options > Ties above/below noteheads: Gap between center of noteheads and tie ends: ¼ instead of the factory 0.
Even with factory settings, I do not see the gap changing any more after the first change in a tie chain. This is probably all moot if there is a buglet being fixed, but FWIW.
With your settings the gap is less (if even) noticeable, but the vertical shift is still there, and I cannot understand why it is the 3rd note.
At first, I thought it to be the very last tie, but adding one more did not move the shift, instead, the tie resumed its correct position.
Here is another section where the 3rd tie (for the lower note) is raised (or are the first 2 ties lowered?)
Only the programmers can tell what is the reason for this.
In the latter image, we also see the “need” for “when ‘belly’ is close to the middle, centre it” as 2 of the 3 ties are in the centre but the third, that (probably) has the same length hangs down too much. (If I have missed any setting for this I would appreciate a tip about it.)
