Hello,
Thank you for contacting Rank Math, and sorry for any inconvenience caused.
I have checked your page, there is Missing field "headline" (optional) warning.
This is just a warning, you can ignore it as it would not affect your rankkings.
However, if you want to fix it, you can go ahead and edit your schema in the Schema Tab

Then, click on add property

Then, enter headline in the attribute textbox and your actual headline in the corresponding textbox.

Once done, save the schema and check your page at https://search.google.com/test/rich-results
I hope this helps. Looking forward to helping you.
This is boring, every thread should I do this?
Hello,
Thank you for the update.
You can set your default headline by heading on your WordPress dashboard > Rank Math > Titles & Meta > Post types:

To use the post/page’s current title for your headline, please use the %seo_title% variable in that section.
I hope that helps. Thank you, and please don’t hesitate to contact us anytime if you need further assistance.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.