I'm not sure either. It's very close if they didn't. In the above pic, it's crystal clear Betts' left shoulder is some distance (a foot?) from the fence. While his arm is angled from his shoulder toward the wall, I think it's a reasonable to conclude the hand(s) in question are in the field of play, since reasonable to assume Betts' glove isn't at the wall yet. It's also reasonable to be wary of a single screen shot as evidence, since it's at a poor angle, and leaves out everything that happens before and after that particular moment. Either way, it's a very close call, and sans clear evidence one way or the other, entirely reasonable to defer to the judgement of the umpire who made the call, IMO.