If you try to upload the one of the attached Word documents (or PDF, PPT), it sometime fails and detect it as an image/jpeg, and leave the workflow instance stale.
Some error related to the image thumbnail creation also indicate that it tries to process the file as an image instead of the original content type (doc, ppt, pdf etc..).
This issue is due to the wrong dc:format metadata created. There is a workaround by extending the DAM update asset workflow model to fix this.
Now, try to upload the word document (or other document type that failed).