The Battle.net application has been experiencing intermittent stability issues.
A recent update to Battle.net was rolled out, and shortly after, users began reporting problems.
Players of World of Warcraft noticed that accounts were disappearing from their Battle.net account list: sometimes a single account goes missing, and other times several vanish at once.
Blizzard Entertainment has responded to complaints from affected players:
“We are aware of an issue causing certain World of Warcraft licenses to not appear in the Battle.net app. Our team is actively investigating and working to restore full functionality as quickly as possible. Thank you for your patience.”
Source: iXBT.games