This is good to know. Frustrating, but still good to know. I've done trades where I attempted to walk back to the airport (even announcing it before I started walking, lol) and the person would either end the session on their side before I could, or ask me why I didn't just hit the minus button to leave quietly. And I had only stopped doing that because I heard vague rumors that it was "unstable" to do so, but seeing proof in this thread cements it in my mind.
Possible data wipe or corruption is a huge deal. I really hope someone at Nintendo is working on it.