Rows disappear on changing the height based on dynamic rows

I am using the datagrid that will act as a tree. The number rows will be increased for populating the child rows, while user expands the tree. Everything is Ajax. Everything was looking good with vestion 2.0.2, but when we updated the version to 2.5.3, few rows at the end started hiding, but the grid height is increased correctly with the empty space appearing in place of the rows hidden.

If i click on any cells of the last two visible rows, the hidden rows appears again, but while scrolling with mouse, it again disappears.

Please help.