On a similar note, I believe I can't be the only one annoyed by the glitching out encounter difficulties!
Going 25n or 25hc? Fine, swap them as you like. Going 10n? Oh right, just go outside for a moment. But change the difficulty to 10hc, YOU CAN'T CHANGE IT TO ANY 25M ANYMORE.
Thinking you're savvy and surely won't get into that trap?
Logout inside a 10n for a while, spend time on some less-or-more-heroic alts, go back and you're suddenly in 10hc.
(Not to mention that Blood Queen on 25m can be as annoying as Yogg-Saron when your DPS is, to name it, relaxed. But no wonder when you happened to rely more on prepatch invasions and pet battles than heirlooms
EDIT: Rule of self-denying message, I used that bugged run to try out the 10n and a Ghoul dropped