We will further investigate on this issue and will log it on our issue tracking system for product team (if required). Currently we are also working on new monthly release of GroupDocs.Annotation for .NET API v17.8.8 which will be available for public use in next 24 hours. Kindly also get a latest API version and give it a try. We will get back to you once we have any further update on your raised issue.
We did further testing and we are finding that it may not be the last comment.
But we are certain that one comment is typically not in the exported Word document.
Perhaps, an indexed is being excluded from the export logic.
Thank you for sharing your further findings, this scenario is logged on our issue tracking system for further investigation and resolution. Ticket id for this issue is “ANNOTATIONNET-497” . If we have any information regarding this issue, we will update you here.