Lightroom mobile(Android) - "Auto add from device" not showing all folders?

I upload raw from my camera to my phone via a FTP server on my mobile when I'm on the road.

I put the photos under /Download/FTP/ which is where I want them.

After that I want Lightroom Mobile to automatically pick them up with the "Auto add" function. However, when I go to the settings for it, with the "Import from all locations" check to off, I only get folders that are under /Pictures on my phone. I can't use FTP to upload the photos under Pictures, because then the RAWs will automatically be picked up by Google Photos, which is not ideal(they are not processed and take too much space).

Why can't we import photos from any location we choose?