A path with all its anchors selected is stored whole (no partial entry), so
pressing one of its anchors looked unselected and replaced the selection with
that anchor alone; the drag then moved just it. Now an anchor of a path
selected whole counts as selected: the press keeps the selection and the drag
moves every anchor. Shift-press still deselects that one anchor.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>