On a purchase I am sending the following to GA:
{
    "v":1,
    "tid":"UA-XXXXXXXX-1",
    "ds":"cloud",
    "an":"App Name",
    "aid":"com.example.appname",
    "ni":1,
    "uid":"AXUflYS8x3",
    "geoid":"",
    "uip":"",
    "t":"transaction",
    "ti":"1000000181XXXXXX",
    "ta":"apple",
    "tr":1.49
}
As per the transaction documentation it looks like only transaction relevant data should be sent and the user documentation is not very specific about which events it should accompany.
Regardless - the event does not seem to unify with any session and as it is being sent from the server (hence the non-interactive ni tag) we are getting no useful data on country, device etc.
So what's missing? How do I unify the transaction with the events that are sent from the client that have all of the interactive event data in them?