I’m having exactly the same problem. I can post the text, but never the image.
It used to work, now it doesn’t.
I’ve tried every single combination – Image post gives me this error:
Array ( [Warning] => [Error] => (#324) Missing or invalid image file )
Text post with attached blogpost with images set to Auto or picking a specific image don’t work.
Sharing a link or attaching blogpost don’t work either.
I tried killing my FB app and re-creating it. Still no joy.