Since yesterday, there is currently there is a widely reported problem the Bitlocker Key section on Microsoft account online is inaccessible, this is a server side fault that Microsoft needs to fix, hopefully they may resolve the problem soon, because many people are trying to access their Bitlocker Recovery Key at the moment.
Last night the Bitlocker Recovery section was not working here, but it is working now, so they must be working to resolve the problem at the moment.