Thanks for reaching out to us. We apologize for the inconvenience. The cause of getting only text files after dragging the .lia file is because that you do not have the PCAD importer installed. To install the PCAD importer, you may follow this guide here: http://blog.snapeda.com/2019/03/20/how-to-install-the-p-cad-importer-in-altium-designer/
After installing the PCAD importer, restart your Altium software and try dragging the .lia file again. The import wizard window should show.
Let me know if you need help with installing the PCAD importer.
Answered 11 months ago.