I tried this under both Win10 and Win7. No problem, everything WAD.
Try this experiment:
- Empty the Normandy Logs folder.
- Start a campaign.
- Save the campaign.
- Before doing anything else, immediately zip up the contents of the Logs folder.
- Exit the campaign EXE.
- Restart the campaign EXE.
- Attempt to load the saved campaign.
- If and when it fails, immediately, before doing anything else, zip up the contents of the Logs folder, giving this second .zip file a different name.
- Attach the two .zip files in a reply post here.
Maybe that will give us some better clues why this is not WAD for you.