diff --git a/app/controllers/api/pm/issues_controller.rb b/app/controllers/api/pm/issues_controller.rb
index 600cf089e..7ec79b5e5 100644
--- a/app/controllers/api/pm/issues_controller.rb
+++ b/app/controllers/api/pm/issues_controller.rb
@@ -243,7 +243,7 @@ class Api::Pm::IssuesController < Api::Pm::BaseController
     belinkable_issues = Issue.where(id: PmLink.where(be_linkable_type: "Issue", be_linkable_id: @issue.id).pluck(:linkable_id))
 
     full_link_issues_ids = children_issues.pluck(:id) | linkable_issues.pluck(:id) | belinkable_issues.pluck(:id)
-    compare_link_issues_ids = (children_issues.pluck(:id) | linkable_issues.pluck(:id) | belinkable_issues.pluck(:id)) - full_link_issues_ids
+    compare_link_issues_ids = children_issues.pluck(:id) | linkable_issues.pluck(:id) | belinkable_issues.pluck(:id)
     i = compare_link_issues_ids.count
     while i > 0 do 
       children_issues = Issue.where(root_id: compare_link_issues_ids)