When documents are being downloaded from NetDocuments, the contents are blank and they do not Check In automatically via ndOffice.
We found that the user had Carbonite Backup installed.
Carbonite will make new documents appear as if they are blank until they have synced. This includes local documents.
In the case of ndOffice, it was trying to sync the Echo Folder but was never able to make any documents placed in it to appear as if they were blank.
Right-click on the ndOffice Echo folder > Carbonite > "Do not back this up". Once that change takes effect everything should open correctly.