This is an expected behavior.
After performing an OCR (Object Character Recognition) on a document such as Word, PDF or an embedded image in an attachment, it may not get indexed when document is a picture or image. As a result, when viewing these items from Analysis & Review in a Text View mode, any words or context inside it cannot be searched since its content is not indexed. The following message also appear:
If there are images in this document, they will not be displayed
This is an expected behavior. Use Native/Image View to view its image(s) instead.