Reported for: WPML Media Translation 2.5.5
Resolved in: 4.3.13
Since recently, uploading a large images in WordPress makes WordPress to generate a smaller scaled-down version of the image.
This scaled image is then being added to the image sizes and being used as a default image for the posts where the larger image should be used.
However, this is not being the case for translated images – instead WPML Media Translation is using the larger image.
You can notice that, because the image in the original language has a “-scale” suffix, while the translation does not.
Our developers are working on fixing this.
As a workaround, you can try installing a plugin and regenerating attachments/media thumbnails from the second language