Why are some entries DKIM aligned but failing SPF?
If you are sending emails through your business domain as "From", DMARC will compare it with the "Envelope From" domain. If both the domains or their subdomains match, SPF is aligned.If "Envelope From" domain does not match with the actual sender's domain ( Organizational domain ), so SPF alignment will fail.
This is a common scenario in automatically forwarded emails, where SPF alignment fails due to the email passing through one (or more) intermediate servers before reaching the final recipient.
Read more about DMARC forwarding