For those having issues uploading photos, this might be your problem.
I did extensive testing on this long back and have reported to microsoft numerous times and on various forums.
When uploading a pic, either in the facebook app, facebook beta, or the windowsphone hub, if you put a line feed in the description text (hit enter) it wont upload.
This behaviour has been consistent for me for a year with every version, every update I retry it and still the error is there.
So it may be that sometimes you describe your photo with more text and decided a new paragraph is required, and on these occasions it wont upload.
Its all irrelevant for me right now, I cant even open the facebook app, it opens for 2 seconds then closes, both beta and regular.....very annoyed. Came here to check solutions for this problem after reading a lot of reviews on the store which have the same problem, saw the photo uploading problem, thought I might be able to help. Good luck!