I’m running an Ubuntu server with the latest nextcloud, 10.0 and added external local disks.
I.e. /media/storage/comics/company/comicname/
but when I open the folder, no files are populated.
My media folders work though.
Has the webserver access to the folders (they must be able to go through all parent folders)? What do you mean with the media-folder works (/media itself)?
I have lots of directories I’ve mounted, other folders like /media/mediafiles/videos loads everything in it.
I chmodded the folder /media/storage/comics to 770 but it doesn’t work.
I am the owner of the folder (as well as the working folders)
You have to find out the difference between the working and non-working folders. If your device is NTFS or FAT, you must add the owner settings in the mount command (or /etc/fstab).
As far as I can tell, I have updated them to all have the same permissions, so, theoretically it should show up, but, I don’t know how to make it scan the files.
I figured it out and used OCC to scan. Not sure what the exact problem was, but I think it was chmodded 660 so it couldn’t be read.
Thanks for helping me debug this 
It should normally run automatically when you add the storage or when you access it for the first time (you have also an option to do this on every access).