RudderStack

We have integrated Rudderstack-PHP-SDK --&gt; GA4, but offline events are not attributed to certain locations, nor ad campaigns. They are being showed as Direct/Unassigned. We obviously need to tie back-end events with front-end sessions which we are trying to do right now.

Does anyone have experience in associating offline events to front-end sessions in GA4?

We are currently sending such payload from our Rudderstack PHP SDK:
               'userId' =&gt; '25706',
               'anonymousId' =&gt; '1947780149.1686557053',
               'event' =&gt; 'minja_test_20',
               'properties' =&gt; [
                 'session_id' =&gt; '1686812151',
                 'engagement_time_msec' =&gt; '100',
               ]

Do you have a clue of what's missing or wrong?