Was having trouble loading from csv files. I had loaded the the files into the project files section of Desktop. Could load or open the folder to confirm the files. But would receive the 'Couldn't load the external resource at: file:///' error.
What I found is two different import folders for the project. The Desktop GUI shows files in the Application/projects/project-**** folder, while the cypher commands import from the Application/relate-data/dbmss/dbms-#### folder. With the different locations having different names for the project. From what I understood, putting the files into the project folder they would be utilized with cypher commands.
I am in Arch Linux (installed directly from the repository). With my db at 5.26.4 in desktop 1.6.0.