Update from Git - Azure Devops Pipeline

Hi, MartinMason 

Update your pipeline's PowerShell script to use the PAT instead of trying to authenticate via Service Principal.

- powershell: |
    $pat = "$(PAT)"  # Your PAT stored securely in Azure DevOps
    $headers = @{
      Authorization = "Bearer $pat"
      "Content-Type" = "application/json"
    }
    $body = @{
      remoteCommitHash = "$(GIT_COMMIT_HASH)"
      conflictResolution = @{
        conflictResolutionType = "Workspace"
        conflictResolutionPolicy = "PreferWorkspace"
      }
      options = @{
        allowOverrideItems = $true
      }
    }
    Invoke-RestMethod -Uri "https://api.fabric.microsoft.com/v1/workspaces/$(PBI_WORKSPACE_ID)/git/updateFromGit" -Method Post -Headers $headers -Body ($body | ConvertTo-Json -Compress)
  displayName: 'Update Power BI Workspace from Git'

For now, the PAT approach or interactive user authentication are your best bets to achieve the desired functionality. Both have their pros and cons, but they can enable automated deployments until Microsoft officially supports Service Principal authentication for this endpoint.