The only way to confirm is to post a full TS,or the CAT and PMT packets to analyze.(better a full TS,though)
But I thought we were coming back here in june 2019,no need to update this thread until new biss is spotted somewhere,pointless to talk about it.
Well, Barney can tell the story much better than I do, but AFAIK the feed started as a regular BISS feed, we even had the correct key just as usual.
Then, 5-10 minutes before the actual event started, the transmission rebranded itself (new service ID and new provider), the known key went down, and after that, while it was still BISS of some kind, the regular methods only threw up a lot of fake positives, thus the real key couldn't be found. In the end, none of us was able to watch the actual broadcast.
Next day (Smackdown) the exact same thing happened, so it wasn't some kind of a technical problem, or a one time only thing.
Given the fact that this feed broadcasted by WWE exclusively to themselves (from the arena to the production studio), so there wasn't a whole wide list of recipients, it is easily possible that the WWE has obtained some new hardware, and since the transmission was broadcasted only to themselves, they could easily use the new format, without worrying that others doesn't have the new equipment.
Reading the EBU guidelines (turn on the scrambling systems only 5-10 minutes before going live), this behavior also fits with the new recommendations.
So while it's only a speculation, given the known facts it could easily be one of the first sights of the new encryption system. Add to this the fact that WWE always have been paranoid of it's feeds, and they also have the money to buy cutting edge new technologies.
This is just speculation on my part, but I think we might just saw the new BISS2 in action.