I cannot get around this issue. I installed the app yesterday, and I keep getting this message when I sign in, and the same from the website. I've browsed other threads with the same issue, but none of the solutions work. Clear cache, update drivers, make sure the firewall allows, make sure antimaleware/antivirus protection allows, reinstall, make sure the date and time is synced, use different web browsers, reset internet options in explorer. Everything given, I've tried, and yet this issue persists. I noticed that if log out from the app, then try to log into the website, it tells me to change my password. But if I log into the app first, to get the sign in unavailable error, then the site, I get the unavailable error. It's frustrating.
