SPF and DKIM Authenticated but DKIM does not appear in source of email

SPF and DKIM Authenticated but DKIM does not appear in source of email

New to Zoho and testing it out. I brought over one of my domains, set it up for email and successfully added and authenticated both SPF and DKIM in Zoho Campaigns. 

With other email hosts that I've worked with, my outgoing email will show Mailed-by: domain.com, and signed-by: domain.com.

Even though my TXT records are verified with Zoho, and have verified on 3rd party sites, only the mailed-by: domain.com appears in my email. If I check the headers, or source for the email, DKIM is nowhere to be found. Only the SPF: pass is mentioned.

This is unlike any other email I have ever set up, so I don't know if the DKIM is in effect even though it was verified. Any ideas before we consider using Zoho for our business needs?