After making any edit in the editor and then previewing the page, a drag/drop group's X and Y position may initially be set to (0,0). The correct position updates after refreshing the page or dragging the group manually. If no edits were made in the editor before previewing, this doesn't occur.
What you might notice
After making any small edit in the editor, the drag/drop group's position shows as (0,0) on first preview
Refreshing the page a second time or dragging the group updates the position to the correct values
This doesn't occur if no edits were made before previewing
Workaround
Refresh the page after the initial load to display the correct position
Drag the group manually to force its X/Y values to update