Embedding PowerBI in Dynamics 365 Portal

[SeanAnderson]

I am attempting to add a PowerBI report into a Dynamics Portal, with row level security ... below are the steps that I have taken so far, which has got me to the point where the report is showing, with the headers (of a simple grid view) but the data isn't showing.

Firstly we note that we have two tenants here, let's call them "corporate" and "public". All of our data is in the "corporate" tenant and the Dynamics365 portal is in the "public" one. We have a Premium PowerBI Embedded instance in both tenants and a Data Gateway running on one of the on-premise servers (within "corporate", that is signed-in with an AzureAD account from the "public" tenant, so that we can read corporate data, from the public tenant. 

I have created two simple tables, (Table 1) USERS, containing a bunch of email addresses that I am testing with, including mine from both corporate and public, along with a basic AzureAD account (minic and end user) in public and a random guest email which isn't in either tenant. (Table 2) PROJECTS, a simple list of projects with a USERID to create the relationship back to USERS.

Created a simple PowerBI report to view the data and published to the Premium workspace of the "public" tenant and checked that it's working in app.powerbi.com

Followed the tutorials for PowerBI Dynamic Row Level Security, parts 1 and 2 to add a role, with the DAX filter on USERS.emailaddress = USERPRINCIPALNAME(), republished this and attached the Gateway.

Followed the Microsoft guide for Setup PowerBI integration with your Power Apps Portal followed by Add a Power BI report or dashboard to a web page in portal to add a liquid tag into a portal page, as follows:

{% assign authType = "powerbiembedded" %}
{% assign roleName = "MySecurityRole" %}
{% assign pathAddr = "https://app.powerbi.com/groups/.../reports/.../ReportSection" %}
{% powerbi authentication_type:authType path:pathAddr roles:roleName %}

Added the "Portal Power BI Embedded Service" user as a member of the Premium Workspace and view the page that I have craeted, one browser instance using my corporate account and one using the account from the public tenant. In both cases, the report displays the headers (Email Address, Full Name, Project Name) but does not list any of the rows. I created a fresh AzureAD account in the public tenant (not any kind of admin) and that only see the headings, too.

From app.powerbi.com, I browsed to the report URL using:

>> the "public" account and I see ALL records - this account is a PowerBI admin and I believe that will override RLS, though, I can go to the RLS of the dataset and "test as role" and it shows the correct records.

>> the fresh "public" account and that gets the sign-in to PowerBI prompt.

Any suggestions as to what I might have missed, would be appreciated.

>> the "corporate" account" and I get an error saying "Sorry, we couldn't find that report. It may have been deleted or you may not have access to view it"

[edit 15/08/2020] having seen a similar post elsewhere, I checked the console for errors and I am seeing the following, but not sure if it's relevant.