In your big dataset example:
-Open dev console
-Select task 111 and 112
-Drag them both below 114
-Now click into dev console. Notice 111 unselects. Even though it looked like it was selected.
Seems like after drop the selection changes but the highlighting stays. Selection should stay
Additionally if you try to drag/drop on your advanced demo you get an error.
gantt.module.js?467719:10 Uncaught (in promise) TypeError: Cannot read properties of undefined (reading '_domData')
at DomDataStore.get (gantt.module.js?467719:10:504180)
at Row.renderCell (gantt.module.js?467719:28:196479)
at gantt.module.js?467719:53:171149
at Array.forEach (<anonymous>)
at RowManager.forEach (gantt.module.js?467719:53:12351)
at Gantt.refreshColumn (gantt.module.js?467719:53:171126)
at gantt.module.js?467719:53:142122
at Array.forEach (<anonymous>)
at Gantt.onColumnsChanged (gantt.module.js?467719:53:142000)
at Gantt.onColumnsChanged (gantt.module.js?467719:53:1010643)
But all the first issue in my post there is no error just confusing to users.