Backups are not created in mode userzip
The backup-mode "userzip" creates a wrong zip-command and no backup is created.
The zip command is using --exclude= wich is an option for tar, not zip. --exclude is also unknown.
Its working with this syntax instead:
sudo -u web1741 find . -group client139 -print -not -name backup* | zip -b /tmp backup/test.zip -y -@
The find is excluding the backup-folder instead of zip as it can not parse -x and -@ together. -y is storing symlinks in my example.