If this problem occurs, please check first if there are really no more files in the directory. Mostly the reason for the problem is that you have set up your own error pages or password protection in the customer interface or one of your scripts has created an .htaccess file.
In these cases you should remove the password protection or the error pages in the customer interface or delete the .htaccess file.
If this did not lead to the desired success, please use the command ls -la to display all hidden files. If there are no files, please contact our support via the contact form in the customer area.