I'm having trouble with certain images displaying in Outlook. I'm using outlook office365 and within the body of the email about half of the images are not downloading. I've tested in gmail and it loads without issue. The mobile version of microsoft outlook displays them all as well.
It is happening with both JPEG images and GIF images.
Emails can sometimes render differently because of the HTML and CSS standards that email clients use, and they can even vary depending on the version of the email client. Here's a help article with some handy troubleshooting tips.
I also wanted to refer you to these related threads regarding images and emails looking different in Outlook: