"File Path" input text from ecommerce doesn't autocomplete when formfilter is enabled

I'm using formfilter to hide some form items to users with permission to manage the store (based on ecommerce).

When I add a "file download product" to the store, I can enter the path to the file in a kind of input text wich has the autocomplete fuction. This function displays a dinamical list of files located into the directory you are looking at.
This autocomplete function seems not to be enabled for users with "view forms without filtering" disabled.

How can I get this autocomplete function to work with formfilter enabled and doing his job?

Thanks in advance for your replies.