lifecycleNotificationUrl endpoint not being called/triggerred from Microsoft's Graph Api when Subscription is about to Expire

Question

I am using graph api's webhooks (subscriptions/change notifications) to listen to changes happening on todoTasks and Events from Outlook. The notificationUrl endpoint is working correctly. I've followed the documentation provided by Microsoft, and I am indeed getting what whas expected and managed to write my business logic further from there.

However, the problem starts when the subscription is about to expire.

The lifecycle url that I've provided is not being called at all! I've tested with notifications created with expiration date set in a few hours and even days. Nothing!

I tested my endpoint and it is indeed OK, public and usable. I am monitoring if the endpoint is being used in the debug logs in Salesforce (as that's the integration that I'm doing). I've also tested another publicly accessible url and monitored it via online tools (so that URL was not related to SF) and nothing is received again...

I do not know what to do. I asked a question on their forum but they do not respond...

I am expecting the endpoint to receive a renew notification so that I can "fire" a PATCH request and update the subscription, prolonging its expiration date.

Example of the way I create the subscriptions (this is one of 4 that I have):

   {
  "changeType": "updated",
  "notificationUrl":[myPublicEndpoint], 
  "resource": "/me/todo/lists/[listId]/tasks",
  "expirationDateTime": "2024-03-08T12:40:00.0000000Z",
  "clientState": "SecretClientState",
  "lifecycleNotificationUrl":[myPublicEndpointThatsNotTriggerred],
  "includeResourceData":false
   }