I had all my assignments handed in (and did well on all of them) except for pset 8 which says right at the top, "if unable to get the Google Earth Plug-in working on your computer, you may skip this problem set."
On 31 Dec, they put a big yellow-highlighted message on the CS50x page on edx with a continually-updating countdown to the second to 6AM. I was able to get pset8 working and handed in before 6AM, but have found myself auto-enrolled in CS50x3/2015 and without certificate, so clearly they did not count that.
I have emailed every address I can find to ask that they consider my case for a certificate as I in good faith met the deadlines they gave, or at least correct the problem so no one else gets screwed by it; and no one has even bothered to answer. I loved this course and I am really upset.
Did anyone else get screwed or was I the only one idiotic enough to trust the most recent communication we'd had from them (the new announcement on edX)?