I have built a folio, works as expected and it has successfully published in DPS and exported to a zip file.
When I build my app in Viewer Builder, I get an error when I submit the zip file - the red outline appears around the box and when I hover over it, the message reads 'Zip/Folio invalid. This Zip/Folio must come from the export facility of Folio Producer'.
There is a large video file in the folio which uploaded fine in folio builder, displays perfectly in Content Viewer.
I have removed the video and rebuilt the zipped folio and it immediately worked, so the video is obvioulsy causing an issue.
The client supplied the video file at over 300mb, which I have compressed to just over 100mb. I have published videos compressed with the same method in other apps and haven't had a problem with them.