EUCOP

A workaround for this problem that works for me:
Within the ‘Edit Package’ screen choose the option ‘SELECT FROM MEDIA LIBRARY’
and then on the tab ‘Upload Files’ go for ‘Select Files’
and select the files you want to upload to the download package
Finalize by tabbing the ‘Select’ button in the right lower corner.

I have the same problem. I have an existing package from which I remove files (this works) and want to add files. All the files are uploaded but only one file is added to (visible in) the package.
The same issue with an entirely new packaged