I created a subfolders and then moved a few design files there. The Model that referenced these design files couldn’t find them. Why?
Steps to Resolve
Please check if you added the path to the newly created subfolders in your configuration variables.
Go to File > Settings > Configuration and open the Configuration Variables. In the opened window search for MS_RFDIR.
These are all your references that are automatically being searched through path references. You probably created a new subfolders whose path is not listed here.
Press the Select button, which is located on the right side. In the navigation window find the path you want to add and add it. Then press done. Now this path will be added to the list and will be available for the references.