You have added attributes to a srcSchema in the XML editor, but no attributes appear in the Structure tab and there are no database updates to apply.
Attributes were defined outside of the root element in the schema.
Make sure that the root element doesn't have a self-closing tag, e.g. <element/> and that the attribute definitions are located between the open and close tags, e.g. <element> ... </element>.
When creating a new schema, before adding any attributes you must change the self-closing root element tag to an open and close tag.