Type: taxonomy field doesn't read current values

So, I have a custom field using the taxonomy type. When I enter information into the field and save the page, the header is updated with the correct values, but the field doesn't show the values saved when reloading the page... Any idea why?

Have you overrided that field in blueprints?

No, I've called it header.jombo (ridiculous nonsense word) exactly for that reason (to not cause collisions with existing variables).

        header.jombo:
          label: Tags
          type: taxonomy
          validate:
            type: array

Try to use it this way:

        header.jombo:
          label: Tags
          type: selectize
          classes: fancy
          validate:
            type: commalist

Well, that works, but it doesn't autofill the existing tags which is somewhat important as I can't expect the end user to remember them all (there are quite a few)...

You mean it doesn't autofill it like the default taxonomy field under "Options" tab?

Exactly right. Editors can't possibly know all current tags in use, so the field needs to autofill them.

Seems like built-in taxonomy uses something else, if you figure out, please, comment here.