Dialogflow Slack integration app_mention not working

app_mention is now supported by dialogflow. All you need to do is subscribe to the following bot events - app_mention and message.group in Slack. And in dialogflow, under slack integration, uncheck Process all messages check box.

The app_mention event is not supported by Dialogflow.

I reached out to both Slack's and Dialogflow's customer service after experiencing the same issues as you.

Slack checked on their side and even took a look at the logs for my bot user and saw that everything seemed to be sent to Dialogflow just fine.

Dialogflow on the other hand answered this:

At this time, the Slack integration of Dialogflow is ideal only for direct message. Bot will respond to any messages with or without a mention.

Unfortunately, we can’t disclose details about our releases until they’re live. We announce all new features in our Change Log: https://dialogflow.com/support/change-log. Stay tuned!

I just hope they'll add support for this some time soon. It's annoying not to have that feature, because now the bot user will either interfere with everything in a channel or only support direct messages. It might help the more people take the time to contact Dialogflow support at https://console.dialogflow.com/api-client/#/support .