Unfortunately, this is a known issue with WordPress when uploading images taken on iPhone or similar devices: https://core.trac.wordpress.org/ticket/14459
We recommend deactivating plugins one-by-one to see if any are affecting the images. Then deactivating the photon settings in Jetpack and checking image dimensions: https://stnsvn.com/help/parker/getting-started/parker-image-dimensions/
You may also want to try regenerating your thumbnails.
Finally, if you are still having trouble we recommend trying one of the following plugins and see if that resolves the issue for you: