Cross Dissolve: Artifact on edges of images.

I have a light jpeg graphic as a base. While cropping image to avoid thick black artifact issue around image, I am simply adding a cross dissolve (transition) at the beginning and ending of a photo image (jpg/png). I am seeing a gray artifact around the edge of the image only during the transition.
Client has detected this and the only work-around is to copy and paste opacity frames of 0-100 for dissolving in and out of hundreds of photos.

Thanks for addressing.

Best,
Ron