Measurement Protocol - WP sending client_id as "client_id" on first event

I'm using the PRO version of the weltpixel GA4 module, using measurement protocol to send some but not all events and like a few people, I've had the issue where the majority of revenue is coming through as unassigned traffic. We're on 1.11.19 but there's nothing in the changelog implying that this is a fixed issue.



If you go into User Explorer for that unassigned segment you can see that the App Instance Id for the majority of them is "client_id"

I've done 2 things to debug this - since we pump our GA4 data into bigquery, I looked at the events for which we have measurement protocol enabled, and it seems that the first event for that session that is sent via MP (we send using MP from begin_checkout onwards), the client_id is sent as the string "client_id"

So I turned on the log, and see the same. Here's 4 log entries, begin_checkout, add_shipping_info, add_payment_info and purchase.

As you can see, the "begin_checkout" event has a client_id of "client_id", subsequent events have the correct id. 

I tried changing which events are sent by MP, but it seems whatever the first event the user encounters, that event is sent as "client_id" : "client_Id"

I'm not quite sure why this is happening or if it's a bug in the module that's been addressed but not logged as a fix.

[2023-06-30T11:10:42.549683+00:00] ga4Log.NOTICE: Begin Checkout event pushed... [] []
[2023-06-30T11:10:42.549797+00:00] ga4Log.NOTICE: Api payload: [] []
[2023-06-30T11:10:42.549823+00:00] ga4Log.NOTICE: {"events":[{"name":"begin_checkout","params":{"session_id":"1688123428","currency":"GBP","value":"44.95","items":[{"currency":"GBP","item_name":"Chrome Bath Caddy with Stand","item_id":"PDN1004","affiliation":"Main Website - Main Website Store - Default Store View","price":"44.95","item_category":"Home Accessories","item_category2":"View All Home Accessories","item_list_name":"Home Accessories\/View All Home Accessories","item_list_id":"113","quantity":1,"item_stock_status":"In stock","item_sale_product":"No","item_reviews_count":"0","item_reviews_score":"0","product_id":"17692"}]}}],"client_id":"client_id","timestamp_micros":"1688123441000000"} [] []
[2023-06-30T11:10:42.582737+00:00] ga4Log.NOTICE: Begin Checkout event pushed successfully. [] []

[2023-06-30T11:11:45.934103+00:00] ga4Log.NOTICE: Add Shipping Info event pushed... [] []
[2023-06-30T11:11:45.934231+00:00] ga4Log.NOTICE: Api payload: [] []
[2023-06-30T11:11:45.934257+00:00] ga4Log.NOTICE: {"events":[{"name":"add_shipping_info","params":{"session_id":"1688123428","value":"50.90","currency":"GBP","shipping_tier":"Graham - DPD - Standard Parcels","items":[{"currency":"GBP","item_name":"Chrome Bath Caddy with Stand","item_id":"PDN1004","affiliation":"Main Website - Main Website Store - Default Store View","price":"37.46","item_category":"Home Accessories","item_category2":"View All Home Accessories","item_list_name":"Home Accessories\/View All Home Accessories","item_list_id":"113","quantity":1,"item_stock_status":"In stock","item_sale_product":"No","item_reviews_count":"0","item_reviews_score":"0","product_id":"17692"}]}}],"client_id":"191511491.1688123428","timestamp_micros":"1688123468000000"} [] []
[2023-06-30T11:11:45.969134+00:00] ga4Log.NOTICE: Add Shipping Info event pushed successfully. [] []

[2023-06-30T11:12:52.940743+00:00] ga4Log.NOTICE: Add Payment Info event pushed... [] []
[2023-06-30T11:12:52.940892+00:00] ga4Log.NOTICE: Api payload: [] []
[2023-06-30T11:12:52.940919+00:00] ga4Log.NOTICE: {"events":[{"name":"add_payment_info","params":{"session_id":"1688123428","value":"50.90","currency":"GBP","payment_type":"Pay by Debit or Credit Card","items":[{"currency":"GBP","item_name":"Chrome Bath Caddy with Stand","item_id":"PDN1004","affiliation":"Main Website - Main Website Store - Default Store View","price":"37.46","item_category":"Home Accessories","item_category2":"View All Home Accessories","item_list_name":"Home Accessories\/View All Home Accessories","item_list_id":"113","quantity":1,"item_stock_status":"In stock","item_sale_product":"No","item_reviews_count":"0","item_reviews_score":"0","product_id":"17692"}]}}],"client_id":"191511491.1688123428","timestamp_micros":"1688123539000000"} [] []
[2023-06-30T11:12:52.975879+00:00] ga4Log.NOTICE: Add Payment Info event pushed successfully. [] []

[2023-06-30T11:12:52.977211+00:00] ga4Log.NOTICE: Purchase event pushed... [] []
[2023-06-30T11:12:52.977273+00:00] ga4Log.NOTICE: Api payload: [] []
[2023-06-30T11:12:52.977296+00:00] ga4Log.NOTICE: {"events":[{"name":"purchase","params":{"session_id":"1688123428","transaction_id":"1000719378","affiliation":"Main Website - Main Website Store - Default Store View","coupon":"","value":"50.90","shipping":"5.95","tax":"7.49","currency":"GBP","items":[{"currency":"GBP","item_name":"Chrome Bath Caddy with Stand","item_id":"PDN1004","affiliation":"Main Website - Main Website Store - Default Store View","price":"37.46","item_category":"Home Accessories","item_category2":"View All Home Accessories","item_list_name":"Home Accessories\/View All Home Accessories","item_list_id":"113","quantity":1,"item_stock_status":"In stock","item_sale_product":"No","item_reviews_count":"0","item_reviews_score":"0","product_id":"17692"}]}}],"client_id":"191511491.1688123428","timestamp_micros":"1688123539000000"} [] []
[2023-06-30T11:12:53.011431+00:00] ga4Log.NOTICE: Purchase event pushed successfully. [] []