Unclear, but I watched 2A unblock (which the 77D blocks) and 6B didn't unblock at the same time. Shows assigned now in EF, and does for flights weeks out too so I think the answer is, strangely enough, no it's not blocked. The sad thing is not everyone agrees with me about 1A on the 752, but there's no doubt that 6/7 ABJK are the first to go on the 772.