sortable not working correctly when contained in "overflow-y:scroll" and "connectWith".

I have two divs (height:50vh) which each contain a table with many rows/items. both tables are sortable and connected using connectWith. Scrolling is disabled on the widget. All works fine. But when the second div is scrolled down and I try to drag an item from the lower table up to the table above, it handles the wrong table/items. It sends the "update"-event for the table/item that is behind the upper table, even if this item is scrolled out of the viewport and not visible. So it should send the update-event on one of the visible items from the upper table.