Takes very long before new files are ready to be watched.

I put files to an external hard drive and plug it to my Shield Pro and then I want to watch via Plex to Infuse on ATV4K. It takes like a day or two before it is available to view. Is it a way to scan straight away so the new file or files are available quickly?

Best would be if I didn’t have to work with the Shield first but start straight with the ATV.