I'm happy to help out.
It's definitely way easier with strong content. :)

How are you putting the photo in? Copy/paste image, upload from your computer, link from a hosting site (like imgur)?

You might just try swapping methods, resave the file as a different image type (jpg, png, etc), or a different image hosting site.

I've had that happen before. Changing stuff fixed it. Upside is that it will fix the thumbnail for you. In steemit.chat just paste post link along with image link of the first post image.