Tried many different approaches for the images to show up inline including the solution referenced above (and the updated version of the solution) for the YAMM tool. Also tried inserting the images directly, via incognito-vetted URLs, from Photos, from my computer, etc. None of these worked for me. In every case, the emails showed up with broken links for the images in the email body but were included as attachments. Image size is not an issue AFAIK since both images were around 100Kb each.
Would greatly appreciate some assistance.