Need help: Import from Aperture to Lightroom with over 100,000 photos in Aperture

Hi all - I'm new to this forum and to Lightroom. Right now I still need to back up Lightroom before I can try the import from Aperture to Lightroom again. The last time I tried, the process just stalled. It didn't seem to be running and there was no progress bar. Should the import be able to handle this kind of volume? Any advice, related knowledge, help is much appreciated. Thank you!