Unable to login to XBL in Windows 10

I am unable to sign into my Xbox Live account in MCW10E 1.0.7.

Sign-in works on my mobile device, but clicking sign-in pops up the XBL screen, but then drops me back to the main menu without having logged in.

Have tried:

• Clearing data in Settings > Apps
• Manually editing options file in %localappdata/packages/minecraft/localstate/etc
• Reinstalling from Windows Store
• Reinstalling XBox app in Win10
• Checking XBox services are running in task manager.

No error comes up in MC; I've once had a XBL 0x3fb error, but the Xbox app seems to login OK now.