ListView content incorrect shifts during simultaneous addition and sorting

The problem appears when adding new items and sorting them at the same time.

To reproduce the bug, run the listViewTest project. At the bottom there is a CheckBox for start and pause adding new items. And ability to sort items in ascending and descending order.
Click on the "Loading status" checkbox. And after a few seconds, change the sort order several times. The content in the ListView will start shifts.

In example there are a class "Storer" which store vector of chars (this class inherited from QAbstractListModel).
There are a class "ProxyStorer" which helps to sort elements (inherited from QSortFilterProxyModel).
There is a ListView that displays a number of rectangles, rectangles contain the char from model and it's X coordinates.