In Avengers: Infinity War Shuri was tasked with separating the mind stone from Vision, and was doing it during the Wakanda battle with Proxima Midnight, Cull Obsidian, and the Outrider army.
Mid way, we see her get interrupted during the process and she starts making large sweeping motions with her arms, which indicates to me, that she was going a lot faster than she felt comfortable, then shuts it down to turn and face the interruption.
At this point, the mind stone should be relatively (50%? 70%?) disconnected, so how does Thanos end up killing Vision (or appears that he has killed Vision)?