Hi,
Do you mean that after you paste a picture in the body of the email, the picture didn’t show up? If so, you could click the “See the full content” button in the email body to see the picture you paste. After you send the email, the recipient could see the picture in the email body.
If so, I did a test in my lab, and I found that if you paste a picture in the email body, it will not show up after saving the email. however, the picture would show up when clicking the “See the full content” button.
1. Click the "See the full content"

2. Click "OK" button of the pop-up window

3. In the new window of the email, we could see the picture.

Hope it makes sense.
BR,
Judy