You can check information about each postback received from the advertiser end, through this, you can check if the postback is correctly placed on the advertiser end or not, you are getting all conversion from their end or not.
To check the postback Log from the side menu, go to Advertiser > Postbacks Hits Received.
Here you can check if there is any issue with the posback received from advertiser end or not, if you find any issue you can go through the troubleshoot article.