fix

app/controllers/users/private_messages_controller.rb

@@ -9,6 +9,8 @@ class Users::PrivateMessagesController < Users::BaseController
     query = "SELECT subquery.*, COUNT(*) message_count FROM (#{subquery}) subquery "\
             "GROUP BY subquery.target_id ORDER BY subquery.send_time desc LIMIT #{limit_value} OFFSET #{offset_value}"
     @messages = PrivateMessage.select('*').from("(#{query}) AS query").includes(target: :user_extension)
+
+    observed_user.private_messages.only_unread.update_all(status: 1)
   end
 
   def create