File browser disappeared

Good morning,
I have a problem with Download Manager. When I add a new file the Browse tab doesn’t shows any dir. It remain empty. (see attached images)
I supposed the cause could be some security setting I hav activated in iThemes Security plugin (there is “Disable File Editor” in the options) but I have unchecked without any result.
Have you some idea about how reactivate this important feature? I need to select files from various dirs.
Thank you very much
Claudio Carli