Unable to save responses as Excel and/or PDF

Hi,

Since two days we are unable to save responses from any form we created in any of the formats available. This feature worked until recently but now it doesn't.

When activating the function by clicking on "Save as Excel" and then selecting either of the tree formats and any combination with "All cells" or "Only export visible cells" after a delay of a couple of seconds the following information is displayed in a pop-up window:

"Acrobat.com could not save the file. The file might be open in another application and cannot be overwritten."

There is only one author registered for this form and the file is not open in any other application. I tried multiple times to log into  Formcentral without any change, the message was always displayed.

How to address this? We need to be able to download the form data!