I was having the same problem and may have a fix for you.
Using Wireshark and Fiddler, we were able to find the login request url that Power BI Desktop uses. It starts with something like:
Taking the complete url from the login request, I pasted it into Chrome and the Adobe Marketing Cloud login appeared. After entering my credentials and logging in, the Chrome screen turned blank.
I then re-opened Power BI Desktop and began the Get Data connection process to Adobe. Power BI immediately established a connection, bypassing the login prompt, and I was able to access our Adobe data in Power BI.
I am, however, experiencing an issue where I can only see 1 of the 3 Instances to which I have access. This may be due to the workaround in connecting to Adobe but I'm not sure. I have another ticket open with Client Care to investigate.
But please feel free to attempt this workaround and hopefully it works for you!
Since I was bumbling along a little bit (and working to get this working on a Windows VM that was a pretty fresh install), I'll add a couple more bits of detail:
Thanks again for figuring that out, Matt. I'd pretty much thrown up my hands and given up.
I am experiencing the same issue. I am working on a windows VM. When I try to login it goes to a grey screen and login fails. Its only happening for me and not my coworkers. I tried the steps above that Matt shared and that didn't fix it. This is very frustrating.
Nothing happens from there. IF I close the gray popup window, then the original prompt changes back to just saying "You are not signed in" with a "Sign in" button below it. But there is also a yellow ribbon that says, "We're unable to connect. Please delete your credentials and try again later."
I'm not sure how/where to delete my credentials.
I'm trying this on a pretty clean Windows 10 install with a fresh Power BI Desktop install.
It is not a connection from Report Builder I am trying to connect from Power BI Desktop to Adobe Analytics as a data source. It works for my colleague so should be some issue with my User ID from Adobe side. I emailed Customer Care email but autoreply says my email is not supported which is very strange.
Have you verified that you are using the latest version of Report Builder? If not, please update.
Then try to follow the trouble shooting techniques from the links Troubleshooting Power BI Integration and Troubleshooting and Best Practices for Report Builder. If not, kindly reach Adobe Customer Care : CustomerCare@adobe.com.