same problem for me too with latest version 1.7.0.22 (Iam on BB O/S 5) - anyone knows a workaround or a way to go back to version 1.7.0.18 - pervious version don't seem to be available for download anywhere..!!
I suffered this exact same problem; having amended the picture size down to "medium", I can now upload to Facebook using the context menu as previously able. I know this is a bit hit or miss as previously other suggestions haven't worked, and it does seem random, but it has worked for me today.