Also having this issue. If I relog it will briefly allow me to launch Hearthstone before it happens again, but eventually it always happens. Oddly enough if I log into WoW, I can then launch Hearthstone only while I am online in WoW, but it will again grey out and say “This game requires you to log in to Battle dot net in order to play.”
And yeah, myself and sometimes friends, but not all friends, appear as “Retrieving details…”