Data Factory Cross Tenant with Azure Git Repo

We deploy out our infrastructure using ARM and configure the Git link as such:

Firstly a variable is configured:

"repoConfiguration": {
      "type": "FactoryVSTSConfiguration",
      "accountName": "[parameters('accountName')]",
      "repositoryName": "[parameters('repositoryName')]",
      "collaborationBranch": "[parameters('collaborationBranch')]",
      "rootFolder": "[parameters('rootFolder')]",
      "tenantId": "[parameters('repositoryTenantId')]",
      "projectName": "[parameters('projectName')]"
    },

and then that variable is used when provisioning the resource:

"type": "Microsoft.DataFactory/factories",
  "name": "[variables('dataFactoryName')]",
  "apiVersion": "2018-06-01",
  "location": "[resourceGroup().location]",
  "properties": {
    "repoConfiguration": "[if(equals(parameters('environmentShort'), 'dev'),  variables('repoConfiguration'), json('null'))]",
    "publicNetworkAccess": "Disabled"
  },
  "identity": {
    "type": "SystemAssigned"
  },

Note that we are setting the Tenant ID for the tenant where Git resides.

Let's just say our emails for Git are: joebloggs@company.com

and for Azure (the other tenant): joebloggs@xxcompany.com

The problem is, the behaviour doesn't match this article from Microsoft.

The behaviour is as follows:

First we log on using our joesbloggs@xxcompany.com email and verify via MFA. The we choose the appropriate subscription and Data Factory. Once that is logged in, we are presented with the following pop up which doesn't 100% match what is in the Appendix of the article:

From here, we get the popup to "Pick an account" and we select the joebloggs@company.com email and go through the usual MFA.

Once ADF loads up, we then have this issue where (and my assumption) it isn't handshaking with the two logins correctly:

When I click on anything in ADF e.g. the toolbox, ADF reverts to this:

Checking the repo setup, it is setup:

I'm at a loss on what could be the issue. Even when manually configuring Git, it works whilst the browser is open, but closing the browser and opening again yields the same issue.

We are also using a Self Hosted IR for ADF.