AEM 6.4 DAM Update Asset Workflow: Thumbnails Not Generated For application/octet-stream MIME Type

[#1]

#DearAEM Experts,

We are migrating DAM content from 6.1 to 6.4 and most of the existing DAM images in 6.1 have jcr:mimeType as application/octet-stream.
(Ex: /content/dam/projects/we-retail/cover/jcr:content/renditions/original/jcr:content)
Issue: AEM6.4 DAM Asset Update Workflow does not generate thumbnails for images having jcr:mimeType (application/octet-stream) but AEM 6.1 does.

Expected: AEM6.4 DAM Asset Update Workflow should generate thumbnails for 'application/octet-stream' mime type images.

Please refer to "jcr:mimeType" property, if you change from application/octet-stream to image/png and re-run the Update Asset workflow the thumbnail images are generated.

Note: Applied AEM 6.4.3 service pack.

Any workaround would be helpful, apart from writing script to update jcr:mimeType from 'application/octet-stream' to 'image/jpeg' (image/jpeg, image/jpg, image/png, image/gif, tiff, etc.,).

[#2]

Can you test in AEM6.5?  I found an issue was resolved in AEM6.5 which may be the same.  If you still have issues in 6.5 it will be good to setup debug for workflow and perhaps open a Daycare ticket.