The JPEG image format is not supported in CONTENTdm. CONTENTdm requires JPG files instead. You will want to convert the file from .jpeg to .jpg in your local imaging software and then add to the collection. If you were able to add the file to the collection, but it is not appearing correctly on the site, you'll have to download any .jpeg files you have into Project client, then replace each image with the new .jpg image file.
Reach out to OCLC Support if you have further support questions or issues.
Please provide Site ID, screenshot or URL of the item you are having difficulty with.