Fixed milestone dropdown label not persisting

app/helpers/milestones_helper.rb

@@ -55,10 +55,14 @@ module MilestonesHelper
     end
   end
-  def milestone_dropdown_selected_text
+  def milestone_dropdown_selected_text(selected)
     project = @target_project || @project || @projects
-    Milestone.of_projects(project).where(title: params[:milestone_title]).first().try(:name)
+    if selected.is_a? Integer
+      Milestone.of_projects(project).where(id: selected).first.try(:title)
+    else
+      Milestone.of_projects(project).where(title: selected).first.try(:title)
+    end
   end
   def milestone_remaining_days(milestone)

app/views/shared/issuable/_milestone_dropdown.html.haml

 - project = @target_project || @project || @projects
 - extra_class = extra_class || ''
-- selected_text = milestone_dropdown_selected_text
+- selected_text = milestone_dropdown_selected_text(selected)
 - if selected.present?
   = hidden_field_tag(name, selected)
 = dropdown_tag(milestone_dropdown_label(selected_text), options: { title: "Filter by milestone", toggle_class: "js-milestone-select js-filter-submit #{extra_class}", filter: true, dropdown_class: "dropdown-menu-selectable",