File owner changes for files copied to the vault

When I drag/drop a file to the vault, the owner of the file changes, when it is in the vault. The vault is located on a cloud drive.

Original:

-rwxrwxrwx 1 root root 615531 Aug 12 2016 testfile.txt

File in vault:

-rwxrwxrwx 1 locuser locuser 615531 Aug 12 2016 testfile.txt

What is the reason for that? I think, there may be problems when I restore files from the encrypted backup and the user rights have changed …