Describe the bug
In a scenario of a DropDownList with virtualization and a valuePrimitve set to true, the selected value disappears if the data in the popup is scrolled.

To Reproduce

1. Open this StackBlitz example
2. Open the popup of the DropDownList and select 'Item 5'
3. Open the DropDownList again and scroll the data down

Expected behavior
The selected value of the DropDownList should not disappear when scrolling its data.

Screenshots