Microsoft Teams not raising events during meeting

Good day,

I have put together a basic bot from your sample projects found here:
https://github.com/OfficeDev/Microsoft-Teams-Samples/tree/main/samples

Adding the application and bot to Teams worked.
I created a tunnel with ngrok and I can see traffic coming in and handle actions taken by the bot. I can communicate with the bot, send replies back etc.

However when I add the bot to a meeting, none of the events are sent to the back-end code. Checking ngrok it does not even receive a call from the bot framework.

I am particularly interested in getting notified when the meeting starts, participants join and other key actions or events.

What am I missing? I cannot find any other settings for the bot that indicate interaction in a meeting that would get routed through the bot framework.

Thanks in advance.

Eugene