Hi Alison
this is a classic example of something that gets reported as a bug in a particular version and where a known fix suggests the cause/solution but in fact it's much simpler than that!
The LO you sent to me via Google Drive has a graphics and sound page as the first page. However that graphics and sound page doesn't have an image added. When you view that from Xerte you get an empty page but able to navigate to the later pages. When you try to view the exported copy it is failing at that empty page. remove the empty page or add and image and re-export and all will be fine. See the copy in Google drive.
For others reading this thread a bit more info about the export options:
Only use the offline export option if you definitely need to extract and view via a local hard drive or usb etc.
For exporting and viewing via a website just use deployment export.
Always publish before export.
For large projects offline export may take much longer than deployment or other export options.
Deployment export will also usually open when extracted and viewed locally via Firefox but other browsers will restrict the xml from loading which is why we have the offline export option.
None of the above resolves an export option for installations that aren't up-to-date with the export fix mentioned earlier in this thread.
HTH
Ron