We have recently came across this error. I will explain as much as I can on the replication steps.
Attached is the sample word document (Doc17.docx) - Please remove the .txt extension.
Highlight the same word (ie. Proc ) and make comment. You should expect two comments on the same word.
Export to Word with TrackChanges.
A [Sequence contains no matching element is thrown].
Below is the Export code used:
Also see the exception and stacktrace attached.
Also, we removed the ability for users to delete annotations by removing the AnnotationAlias::Groupdocs.Common.AnnotationReviewerRights.CanDelete in the AccessRights.