The issue is that the photos load sideways into FB, but not consistently.
You could try to rotate what you upload so that when ends up in FB, it is right side up, but that would be trial and error. I have not tried to fix it when it happens to me. The uploader in FB is such a pain, that I have little patience for trying to make it turn out right. Others have resolved the problem. I just need to learn how to do it.