Problem embedding report - "This content isn't available"

I'm going to wrap this up by clarifying my use case and explaining what I did to work around my issue.  First of all, I'm following the "User Owns Data" scenario, or "embedding for your organization" depending on what documentation you're looking at.  The goal is not to use a master account to authenticate, but rather for the end user to authenticate with his/her account and then be presented with the content that they are authorized to view.  I'm building a custom portal to improve upon the user experience provided by powerbi.com, and adding metadata features in the process.

The main factor with my issue turned out to be the fact that I was opening a new browser window in order to display the embedded report/dashboard.  I never discovered why that poses a problem, but I have successfully worked around the issue by instead displaying the embedded content in an overlay that takes up the full browser window.  The only properties that I need to pass into the config object to the powerbi.embed function are type, accessToken, and embedUrl.  I don't have to deal with embed tokens at all to make this work.

I will also mention that I had a very frustrating experience dealing with Microsoft tech support on this issue, so I'm happy to clarify anything about my solution for people that might stumble upon this post.  I opened a support incident through my MSDN account, and ended up spending many hours over the course of several weeks providing diagnostic information to the Power BI product team.  They really never did anything for me except ask me to jump through lots of hoops, which I did, and it never got me an answer to my question about why I got an error when embedding the content in a new browser window.