Dragging multiple selected elements
To reproduce: Select any two notes (either using Ctrl+LMB for a discontinuous selection, or Shift+LMB-drag for a range selection). Left-click-and-drag either of the notes.
Expected behaviour: In other applications (e.g. Microsoft Word, Adobe Illustrator), when multiple elements are selected, left-click-and-drag repositions them all simultaneously.
Observed behaviour: When the left-click-and-drag operation begins, the multiple selection is dismissed. Only the note under the mouse cursor is selected, and therefore only that note's pitch is changed by the subsequent drag-and-drop operation.
I'm aware that it's possible to drag all notes within a range selection by holding down Shift+LMB when the selection is first created, then dragging-and-dropping from there. However, I believe a simple LMB drag-and-drop, without any modifier keys, would be the more straightforward option.