DS could not upload his work on either of the Physics C exams he took and must retake. Not the end of the world and he has a pretty good attitude about it but CBs reaction has been disappointing, i.e., none except for saying old browsers.
I am not a techie person but son is and says that is definitely not the case for him. In addition, he did some sort of demo a few days before the test and was able to successfully upload so it seems unlikely that there was a technical issue on his side if it worked on the demo.