Hi @tellstevens
It seems you have another field group with the same name (breed) registered via PHP. You can see that the page returned a field object with “field_breed” as the key. Could you please check your template and remove that code? This page should give you more idea about it: https://www.advancedcustomfields.com/resources/register-fields-via-php/.
I hope this clears things up 🙂
