Facebook external ID
Budget: $10 – $30 USD
I don't think there's a problem, it was set up on Wix which has an integration with FB, but maybe someone knows better:
"Server External ID Not Matching to Pixel External ID for Lead Event
You're sending the external_ID parameter for your Lead event from your server, but you're not sending the external_ID parameter for this event from your pixel code. If you send external_ID for an event from your server, you should also send it from your pixel code for best results.
This may cause issues with the attribution and delivery optimization of your ad campaigns."
"Server External ID Not Matching to Pixel External ID for Lead Event
You're sending the external_ID parameter for your Lead event from your server, but you're not sending the external_ID parameter for this event from your pixel code. If you send external_ID for an event from your server, you should also send it from your pixel code for best results.
This may cause issues with the attribution and delivery optimization of your ad campaigns."