I follow this repository <https://github.com/microsoftgraph/msgraph-training-changenotifications> to implement the changes notifying on sent mailbox. So whenever user send a message, I would like receive a notification. Everything work fine if I test it on Windows machine or on outlook web app, however it doesn't work if I test it on Mac OS. Do you have any idea why it could happen?

My testing Mac OS version: macOS Sierra version 10.12.6
Outlook version: Outlook for Mac, version 16.29 (19090802)