I think this is related to the missing card issue, but I currently have a highlander hunter deck that initially had Ragnaros when I built it. I got the missing card graphic after Battlegrounds came out, but got that to resolve by opening the deck in editor and saving it again (unchanged). Only now instead of Ragnaros, it lists Sandbinder in my deck list. If I copy/paste the deck string, it also says Sandbinder and not Ragnaros, but if I actually play the deck, Ragnaros is still there, and Sandbinder isn’t. This was an issue recently in a tournament where my decklist didn’t match what I was playing because of this.
I have the same problem:
In my case the two “special event” cards I put in are not visible in the editor, instead I have an older version of my deck in there. When I play, I have the cards I expect.
I asked Support to check my account to confirm what they see on their end, and thus help troubleshoot the problem. Instead I got a cookie-cutter reply to pots here (already done) and delete all my decks and re-do them from scratch, which I may do soon-ish. Certainly, for a tournament, I would advise everyone to double or triple-check, and to rebuild the deck from scratch to make sure the lists agree.