It seems the issue here is that you have Instant Mode enabled while also drawing the curves manually. I don’t think there’s any bug here (aside from the desync at the end).
When you draw a pitch curve manually it is not strictly associated with the note, it is added to the Pitch Deviation parameter which you have minimized at the bottom of the screen. This parameter curve is applied additively to the original pitch.
When you resize or move the note, not only are you “leaving behind” your manually-drawn curves, but Instant Mode will re-generate its pitch because the note’s context has changed (naturally, a longer note has a different pitch pattern than a shorter one, as does a note closer or further from other notes).
The generated pitch will be combined with your drawn pitch deviations additively (if they still overlap), which results in the odd curves. Since the original generated pitch curve is not the same as the new one, the additive result will inherently be somewhat nonsensical.
Additionally, when you move a different note into the same position as the original note used to be, it will be affected by those parameter curves that were left behind (which you can see by expanding the panel at the bottom). Again, since the new note has a different generated pitch pattern than the original one, this will produce a somewhat nonsensical result.
You could move the parameter curve along with the notes, but this wouldn’t really matter if you have Instant Mode enabled because it’s still going to generate a new base pitch curve for the note based on its context.
You can entirely resolve this issue by disabling Instant Mode. If you want to re-generate AI pitch deviations for a note after changing it, run Auto Pitch Tuning manually (this is what Instant Mode is already doing automatically when you change the notes, you’re not losing out on anything except for AI Retakes, which you don’t seem to be using anyway).
Alternatively, open the parameters panel and delete the manually drawn pitch curves so they do not conflict with newly generated ones.
This will be easier in 1.9.0 where each note can have its pitch mode set to manual or auto, without being a project-wide setting like Instant Mode.
Using 1.9.0 (or the already-available beta release) you can easily “lock” an AI-generated pitch curve by setting a note to manual mode, and then its pitch will not be recalculated when it is modified. You will still need to move the parameter points with the note. They can be selected by right-clicking the note, clicking “Select Parameters for Note”, then repositioning the entire selection.
