修复

app/services/api/v1/issues/create_service.rb

@@ -69,7 +69,7 @@ class Api::V1::Issues::CreateService < ApplicationService
       if @root_subject.present? && @pm_issue_type.to_i == 4
         @root_issue = Issue.find_by(subject: @root_subject, pm_issue_type: 4, pm_project_id: @pm_project_id) 
         unless @root_issue.present? 
-          @root_issue.create(subject: @root_subject, pm_issue_type: 4, pm_project_id: @pm_project_id, status_id: 1, priority_id: 1, tracker_id: Tracker.first.id, project_id: @project.id, author_id: current_user.id)
+          @root_issue = Issue.create(subject: @root_subject, pm_issue_type: 4, pm_project_id: @pm_project_id, status_id: 1, priority_id: 1, tracker_id: Tracker.first.id, project_id: @project.id, author_id: current_user.id)
         end
         @created_issue.root_id = @root_issue.id
       else