Completed orders sometimes receiving abandoned cart emails - associated quotes failing to sync with "Resource Not Found : The requested resource could not be found"

[samsteele]

We're seeing abandoned cart emails being sent out to customers that have completed their orders. For these orders, the ebizmarts_ecommerce cron containing the quote completes succesfully but there are entries in the mailchimp_errors table stating that the associated quote failed to sync with a 404 "The requested resource could not be found" error.

Preconditions

• magento/product-community-edition @ 2.3.4
• mailchimp/mc-magento2 @ 102.3.37
• ebizmarts/mailchimp-lib @ 3.0.31

Steps to reproduce

Not known, seems random, hoping you can advise.

Actual and Expected result

Expected Result -
When an order is placed, the associated quote is deleted from Mailchimp which prevents an abandoned cart email being sent out.

Actual Result -
When an order is placed, the associated quote is sometimes not deleted from Mailchimp and the customer receives an abandoned cart email for an order that they completed.

Additional information

Example of some errors from the mailchimp_sync_ecommerce table attached. All associated quotes are intact and marked inactive.
mailchimp_sync_ecommerce_errors.zip