I've updated an IP address or Host in my SPF Record, but the result is still failing from the DMARC Aggregate report dashboard.

When an email is sent, it includes two main addresses: the "From" address, which is the address that the recipient sees, and the "Return-Path" address, which is the address that bounces are sent to. The SPF record for a domain specifies which IP addresses are allowed to send an email on behalf of that domain. However, the SPF record only applies to the "Return-Path" address, not the visible "From" address. This means that if the "Return-Path" does not match the "From" address, the SPF check will fail. This is a well-known case if you're using ESPs such as Mailchimp, Active Campaign, and others that keep their own Return-Path address to handle your bounces.