S2S events have to be modified a bit, for them to be considered for event-triggered campaigns. There is a flag you need to pass as part of S2S events.

You should use an additional key "real_time_action": "true" in the API request which can be added while sending the events to us. 

PFB the sample request:

{
"type": "event",
"customer_id": "1234567890",
"actions": [{
"action": "Set MPIN Failure",
"real_time_action": "true",
"attributes": {
"date": "2017-02-06T15:49:28.744Z"
},
"platform": "IOS",
"app_version": "2140",
"user_time": "1486376368",
"current_time": "1486376368"
}]
}

The presence of this key in your request tells our system that these events have to be considered for event-triggered campaigns.

If you are still facing any issues, please write to us at; support@moengage.com