You have the same problem here:
Problem is in your ViewBag property name. Because it is same as your property in Model it will not work. You should just change name of your ViewBag prop to something else, like:
ViewBag.NewsItemList = new SelectList(ViewBag.NewsItemId.Items, "Id", "Name", item.NewsItemId);
and on View
@Html.DropDownList("NewsItemId",ViewBag.NewsItemList as SelectList, string.Empty,
new { @class = "form-control" })