I cannot connect to a SharePoint Online site from SharePoint Designer 2013.
When I try to connect to the site, it asks me to log-in, however, when I enter my credentials, I get this error:
I'm sure the details are correct.
The account has a SharePoint Admin role in O365 and is a site collection owner.
All the other tenants I manage are working fine, as this one used to as well.
I tried clearing the browser and SPD caches, also re-installing the SPD 2013, but that didn't fix it.
I assume this is an authentication issue, but I can't figure this out... The SPD settings in central admin and site collection settings are all fine as well.