Hi @dcullen ,
There is an announced issue published in Support forum, see :
Power BI users who installed the August or later versions of Power BI Desktop may encounter issues signing in to the Power BI service through the desktop application. As a workaround users can follow the steps in this guide to extract the MSI from the downloadable package, uninstall existing package and re-install using the MSI executable. Power BI Engineers are working on a fix and it will be packaged with February 2020(SU02) release of Power BI desktop.
You may try to update the Power BI Desktop to lastest version 2.76.5678.782.
In addition, there are two primary reasons for sign-in trouble: Proxy Authentication errors and Non-HTTPS URL redirect errors.
To determine which problem is causing your sign-in issue, the first step is to contact your administrator and provide diagnostic information so that they can determine the cause of the issue. By tracing issues associated with your sign-in problem, administrators can determine which of the following errors apply to you. See more: https://docs.microsoft.com/en-us/power-bi/desktop-troubleshooting-sign-in.
Best Regards,
Amy
Community Support Team _ Amy
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