Issue downloading package with multiple files

Hi:
We have used the pro version on many websites and there is one that is having a weird issue. If you upload more than one file to a package and try to download the whole package using the DOWNLOAD all button, the page goes blank and shows a message of “File not found!”. However, the same package allows us to download the files individually and View the files with the WPDM – PDF Viewer addon. The files are on the WordPress dashboard but the package is not downloading all at the same time. Do you know the reason for this issue?? Thanks