Cannot import included .h / .hpp files properly.

I would like to connect remotely to development environment on Docker to enable syntax highlighting, etc.

Almost all libraries（ROS, Boost, etc）work correctly highlighting, code completion with connecting remote environment.
However, one libraries have errors.

As shown in the first image, file list is correctly recognized in External Libraries, but it shows "Invalid Symlink" and an error occurs when I try to #include it.
Also, I cannot see what is in the source code.

I can check the path of hpp files from the top of the image. 
(For example: <<remote>>/home/user/ros_custom_messages/install/ros_custom_messages/include/ros_custom_messages/msg/detection_finish_message .hpp) 
I checked these files in the Docker container are actuality files and not symbolic links.

I am having trouble figuring out where to start debugging this.
Any advice would be appreciated.