Facebook bot not receiving messaging_game_plays webhook events even though webhook is subscribed to those events

I'm testing a facebook instant games app and want my bot to collect messaging_game_plays events to log user data at the end of a play session.

I've set up an app page, app, and uploaded a build that I have moved to the testing stage. I also have a bot with a public webhook that I have successfully verified. The webhook is currently subscribed to messaging_game_plays as well as messages. I have simple echo functionality built into the bot and can spin up the messenger app on my phone, message the page, and receive an echo perfectly.

The problem arises when I go to the games section of my messenger app, play the game, and then exit the game. I expect my bot to receive a messaging_game_plays event per https://developers.facebook.com/docs/messenger-platform/reference/webhook-events/messaging_game_plays/, but I don't receive any indication in the logs of the bot server that anything has called the webhook (even after waiting a significant amount of time).

So my question is/questions are: am I missing something that is required for the messaging_game_plays to be sent to my bot? Is there anything that I need to add to my app-build specifically for this event to trigger? Is launching the game on my phone and exiting the game sufficient for testing this event?

I've searched forums and documentation with no luck but maybe I've missed something along the way. I have checked this question: Facebook Messenger webhook setup, but not triggered, and that helped me successfully trigger messages events which I am getting, I just can't seem to collect messaging_game_plays events.

I am rather new to this process so I may be missing something small, any help would be greatly appreciated!

For reference:

app webhook subscriptions

What does your fbapp-config.json file say? If your bot opt-in parameter is 'opt_in_dev' or 'opt_in_public' you will need to call the subscribeBotAsync method to subscribe your user to the bot before any webhooks will be sent.

Messenger bots will need to be opt-in only from January 19th (see here: https://www.facebook.com/fbgaminghome/blog/important-game-bots-update).

We're making this change to ensure a better player experience.

If you want to transfer player data without requiring the bot to be opted-in, you can use standard JavaScript fetch/XMLHttpRequest with getSignedPlayerInfoAsync to avoid tampering.