Hi @bbweiners. Thanks for posting this, as it uncovered a caching issue which will be fixed in the next beta, which will solve the issue with the black bars.
However, you may want to add SelectOffsetProperty to your wheel so that the selected item will always appear on top.
<coverFlow:FlowControl x:Name="FlowControl" Grid.Column="1" Grid.ColumnSpan="3" Grid.Row="3" Grid.RowSpan="1" NavigationRows="0"
Rows="1" ItemSpacing="-0.175,0" Endless="True" SelectedScale="1,1" SelectedOffsetProperty="0,0,1">