Spring JPA can't search for nested object despite cascade attribute set

so I have an object Product with, let's say, private String name and private Origin origin.
Code is as follows:

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
@Data
@NoArgsConstructor
@RequiredArgsConstructor
@AllArgsConstructor
public abstract class Product {

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private long id;

	@NonNull
	private String name;
	@NonNull
	@OneToOne(cascade = CascadeType.ALL)
	private Origin origin;
}

Now I'm using a data loader to add some products into the database on startup like this:

(Wine extends Products and adds a few more Strings)

repository.save(new Wine(
	"Test wine"
	new Origin(
		"Crete",
		"Greece"
	)
));

Additionally, I have a search endpoint where I can search for either the name or the Origin.

public Page<Wine> searchProducts(
	@RequestParam(name = "text", required = false) String searchTerm,
	@RequestParam(required = false) Origin origin) {
	return wineService.searchWines(
		searchTerm,
		origin
	);
}

and in the wine Service, I create a query using specifications. Putting them all in here would be overkill so just take a look at this:

public static Specification<Wine> hasOrigin(Origin origin) {
	return (root, criteriaQuery, criteriaBuilder) -> criteriaBuilder.equal(root.get(Wine_.ORIGIN), origin);
}

Strangely enough, it seemed to work some time ago but now it doesn't. Now, if I search for a Wine with a certain origin, it just says:
> org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: [censored].backend.model.Origin

How do I fix this? I've seen like 5 different posts regarding this problem and ALL of them said "well, just add cascade ALL to the Object" but I've already done that from the beginning.

Edit:
Origin Entity code:

@Entity
@Data
@NoArgsConstructor
@RequiredArgsConstructor
@AllArgsConstructor
@Table(name = "regions")
public class Origin {

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	@JsonIgnore
	private long id;

	@NonNull
	private String region;
	@NonNull
	private String country;
}

First join with Origin then create two Predicate and add them in builder and return.

public static Specification<Wine> hasOrigin(Origin origin) {
    return new Specification<Wine>() {
        @Override
        public Predicate toPredicate(Root<Wine> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
            final List<Predicate> predicates = new ArrayList<>();
            Join<Wine, Origin> originRoot = root.join("origin");
            predicates.add(criteriaBuilder.equal(originRoot.get("country"), origin.getCountry()));
            predicates.add(criteriaBuilder.equal(originRoot.get("region"), origin.getRegion()));
            return criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()]));
        }
    };
 }