OK, so this has worked for me having web login issues:
Login to your account settings with https://www.evernote.com/Settings.action
Under Evernote Web Select 'Go back to classic version'
Click 'Go to Notes' at top right
Evernote opens OK in classic format.
A popup invites you to try the latest version, which then works as advertised.
My only concern is that this is the second day I've had to do this to regain access.