I am having the same issue.  The website here for Mojang Studios says this has been resolved but it hasn't cause I'm still trying with no success to log in!  I am also having an issue with which version fo the game I purchased.  I purchased the Hero Pass and I can only download Windows 10 Edition.  I do have the ability to update to the hero pass as the website tells me I should have the option to do.  I was able to play the game about 5 hours ago this afternoon but now I can not sign in on any of my PCs.  It claims here that this issue has been resolved but I am still having the issue so it has not been 100% fixed yet.