The session_id=-1 when we use segment send data to amplitude

Our system is Android mobile, when we use segment send data to amplitude, we found the session_id=-1, and we don not konw why? 

{
  "$insert_id": "ad359f15-3f6c-44fe-8a7d-51abe6d1fa5d",
  "$row_source": "realtime",
  "$schema": 12,
  "_time": 1634624174745,
  "adid": null,
  "amplitude_attribution_ids": [
    "d63abe7cdc0f0b2aa76ae262402f7e03"
  ],
  "amplitude_event_type": null,
  "amplitude_id": 251319235937,
  "app": 346475,
  "city": "Beijing",
  "client_event_time": "2021-10-19T06:16:14.745",
  "client_upload_time": "2021-10-19T06:16:27.923",
  "country": "China",
  "data": {
  },
  "device_brand": null,
  "device_carrier": "中国联通",
  "device_family": "Redmi Phone",
  "device_id": "c6adc3fd07f5e282",
  "device_manufacturer": "Xiaomi",
  "device_model": "M2006J10C",
  "device_type": "Redmi K30 Ultra",
  "display_name": "Page Viewed",
  "dma": null,
  "event_id": 118285483,
  "event_properties": {
    "app_country": "ID",
    "page_path": "/account"
  },
  "event_time": "2021-10-19T06:16:14.745",
  "event_type": "Page Viewed",
  "group_properties": {
  },
  "groups": {
  },
  "idfa": null,
  "ip_address": "103.90.177.233",
  "is_attribution_event": false,
  "language": "Chinese",
  "library": "segment",
  "location_lat": null,
  "location_lng": null,
  "os": "android 11",
  "os_name": "android",
  "os_version": "11",
  "partner_id": null,
  "paying": null,
  "plan": {
  },
  "platform": "Android",
  "region": "Beijing",
  "sample_rate": null,
  "server_received_time": "2021-10-19 06:16:27.923000",
  "server_upload_time": "2021-10-19T06:16:27.942",
  "session_id": -1,
  "start_version": "1.0.0",
  "timeline_hidden": false,
  "user_creation_time": "2021-10-15T09:38:05.579",
  "user_id": "801ebeea3212d50e2650513015b60074",
  "user_properties": {
    "anonymousId": "73a7c091-f0ef-4037-8c44-754a0ff78443",
    "userId": "801ebeea3212d50e2650513015b60074"
  },
  "uuid": "19c1c607-30a4-11ec-b00f-066df468c0f1",
  "version_name": "1.0.0"
}