Having the same problem Derek mentioned here in the comments, which got no response

What record name should the txt record be?

https://support.zendesk.com/hc/en-us/articles/4408832543770/comments/4408851169946

I have a TXT record under the record name @.domain.com

which contained already one spf value, and added

include:mail.zendesk.com

as in the tutorial.

but i cannot find it in dns lookups (when using lookup to domain.com it indeed resolves to the value I expect, which is defined in another TXT record with the name domain.com)

Any idea?