Some causes might be:
- Adding your PDF from either network location or a remote drive. PDF files must be stored locally on your computer before importing them.
- If your PDF contains special characters or symbols within its name. Or, if the location of your PDF(s) contain special characters or symbols.
For example, if the folder they reside in has special symbols such as ¢ é í ó ú £$ ©. Try to copy and paste your PDF to your desktop before importing. - A Firewall could be blocking the upload of your Flipbook.
If the problem persists, please send support@3dissue.com your log folder. This folder should be located within your project folder after attempting to upload (usually around 44%).