How to retrieve learning Content details for the default sources using Microsoft Learning Graph APIs

Hi. I am working on a new project to integrate Viva Learning with PowerApps. My goal is to show all recommended courses to the users in the PowerApps application. I've been testing the Microsoft Graph List learningCourseActivities method and it is working as expected.  The problem that I am facing is that for the learning sources enabled by default (LinkedIn Learning, Microsoft 365 Training, Microsoft Learn) the List learningCourseActivities method returns no value for learningProviderId. I've been trying to use List learningContents method in order to retrieve the Course details assigned to the user however this method requires learningProviderId as a mandatory parameter. I've tried to use NULL and empty values for learningProviderId but with no success. So far I've  not been able to retrieve learning content details for the Viva Learning default sources. Is there a way to retrieve course details from default sources? 

Bellow you can find the response for a List learningCourseActivities method showing 2 courses from default source assigned to a user. 

{
"@odata.context": "https://graph.microsoft.com/v1.0/$metadata#Collection(microsoft.graph.learningCourseActivity)",
"value": [
{
"id": "c946a1df-85be-4a78-957b-66bce7217219",
"externalcourseActivityId": "2dae87aa-6ba7-4715-b23d-b34864e109db",
"learningProviderId": "",
"learningContentId": "30b62ea0-1362-4635-a506-3f32434c82a8",
"learnerUserId": "bd618954-0d67-42eb-a779-7510ac60a6f7",
"completionPercentage": null,
"status": "notStarted",
"completedDateTime": null
},
{
"id": "31ee06b3-8efb-4882-86ec-873d6063208c",
"externalcourseActivityId": "115f1a79-972d-455b-8097-de492a421d95",
"learningProviderId": "",
"learningContentId": "6fd7023e-01f2-4413-ba99-f6014915e3f2",
"learnerUserId": "bd618954-0d67-42eb-a779-7510ac60a6f7",
"completionPercentage": null,
"status": "notStarted",
"completedDateTime": null
}
]
}

Thank you