Files copied via System to users file path are not shown

If i copy some files via WebDAV from external to the Users File Folder, i could see this file in the Files App, also i see anything, i copy WebGUI. But if i copy a file from a other path via cp command, the file is not visible in the files App. I have checked file ownership and Permissions, they are the same, as for all the other files.

This runs me in some problems: I backup my Photos from my Smartphone via SCP / SSH every night automatically, if my Phone is in my WLAN Network and is charging up. Now i would like to make a Symlink from the Backup Folder to the Files Folder for Nextcloud and access this the Backup Photos. It seems, that this does not work, the way i expected.

Any ideas, how i can work with Symlinks?

That is a known behavior, you are not supposed to make changes to the data-directory manually. For such operations, you can use the external storage feature.
https://docs.nextcloud.com/server/9/admin_manual/issues/general_troubleshooting.html#debugging-sync-issues

There is a good overview:

thx. I have found a Parameter for the config.php “filesystem_check_changes” and set this to 1. Now i could see the changes.

My Problem with the External Storage App is, that, if i enable the App, i cant use the “Stay logged in” Feature. Or is there a way to use it also in case of the External Storage App?