Both ends of that operation classify here so they can never disagree: the model, which performs the shift, and the drag preview, which has to say whether a release will be refused before the model is ever called. Applies to a cut and destination on the SAME sheet; a cut lifted from another sheet is always InsertCutShift.Blank, its gap having nothing to close into.
What becomes of the space a CUT range vacates when its block is INSERTED elsewhere - the Shift-drag drop, and the
insertFrom({ isCut: true })behind it.