As you mentioned, it resolves fine, so it is not a DNS issue.
Unfortunately I am afraid I cant tell you what their issue is. That is something they need to clarify. That record points to where it should. You can only send them the following output and ask for clarification
I’ve written to cleverreach and they agreed that the behaviour of their side (not accepting mailings.jowissa.com) is weird. The provided a manual work around and solved the matter… Cloudflare side all OK.