WhatsApp contact not detected despite correct number formatting

As a user, I am trying to send a message or a resource (like a video) to a contact via WhatsApp from the SAGA app. The contact's phone number is saved correctly in the E.164 format (e.g., +393293224332) without any spaces. I have verified on my phone that this contact does have an active WhatsApp account. However, the SAGA app shows an error message stating the contact does not have WhatsApp, preventing me from sending anything.