Problem 

The failed numbers in the campaign stats donut and the error breakdown do not match.

Explanation

• The formula used to calculate failures in campaign statistics is Sent minus Delivered (Sent–Delivered).
• The number of campaign errors could be higher due to various issues listed as failed to send according to the campaign's design.
• Even though these errors occur, the statistics team may not include them as actual failures.
• Those excluded errors could relate to a failure in personalization.