A couple of questions:
-You said the recipient gets an empty message. If you have added a written text message under the image, does recipient get/see the written part of the message?
-Is this happening with one recipient or with all recipients?
-if you take a test *** with the cam built into the MBA(don’t process the image at all) and send it to the recipient using Share>messages, do they successfully see that image?
-if you use your iPhone’s iMessage to text the same image to the recipient, does the recipient now successfully see the image? [after sending the text image from the MBA, that will now be in your iPhone’s iMessage conversation with the recipient].
-What happens if the recipient texts an image to you, do you see the image in iMessage on the MBA?
what I’d look to do (and why I asked the questions above) is isolate this down to who/where the issue lives. This could be your MBA, or the recipient’s device (for some reason maybe it can’t read the *** format you’re sending), possibly filtering by your ISP or telco. I use iMessage on my MBA often to send/receive images.