Unable to hide element category in a view in Revit file - revit-api

Question

I want to hide certain elements in the view.
I managed to hid (with view..HideCategoryTemporary) all the elements I wanted except the marked one in the picture attached.
3D_House_before_hide
Element snoop
This element is a building section of category OST_Viewers.
Manually hiding the element category via the view works, but fetching all OST_Viewers in the code and hiding them does not work.
The following code contain the building section elements in addition to the grids,
FilteredElementCollector viewers_sections = new FilteredElementCollector(doc, v_id).OfCategory(BuiltInCategory.OST_Viewers);
FilteredElementCollector grids = new FilteredElementCollector(doc, v_id).OfCategory(BuiltInCategory.OST_Grids);
FilteredElementCollector elements_to_be_hidden = new FilteredElementCollector(doc, v_id);
elements_to_be_hidden.UnionWith(viewers_sections).UnionWith(grids)
foreach (Element e in elements_to_be_hidden)
{
cur_view.HideCategoryTemporary(e.Category.Id);
}
I've checked that viewers_sections contains the mentioned building sections however it is not hidden from the view.
After hide
How do I hide these building sections?

Answer 1

Please use View#SetCategoryHidden instead to turn off the visibility of the category, the result of the View#HideCategoryTemporary will be reset after closing the file. Here is the working example:
var gridCate = this.Document.Settings.Categories.get_Item(BuiltInCategory.OST_Grids);
var sectionsCate = this.Document.Settings.Categories.get_Item(BuiltInCategory.OST_Sections);
using(var trans = new Transaction(this.Document))
{
trans.Start("Hide Grids & Secions");
this.ActiveView.SetCategoryHidden(gridCate.Id, true);
this.ActiveView.SetCategoryHidden(sectionsCate.Id, true);
trans.Commit();
}