JPA @ManyToMany association not fetching owner class' collection

Question

I have a simple Many-to-Many relationship between a User and Role entity. The tables are correctly created. Every time I add a role to a user, the USER_ROLE table is correctly updated with the user_id and role_id. But when fetching all the users, the roles collection is always empty.

User.java

@Entity
@Table(name = "USER")
@Builder
@Data
@NoArgsConstructor
@AllArgsConstructor
@EqualsAndHashCode(callSuper = true)
public class User extends BaseEntity {

    @Column(
            name = "USERNAME",
            unique = true,
            nullable = false
    )
    private String username;

    @Column(
            name = "PASSWORD",
            nullable = false
    )
    private String password;

    @Column(name = "DEPOSIT")
    private int deposit;

    @ManyToMany(
            fetch = FetchType.EAGER,
            cascade = CascadeType.PERSIST
    )
    @JoinTable(
            name = "USER_ROLE",
            joinColumns = @JoinColumn(name = "USER_ID"),
            inverseJoinColumns = @JoinColumn(name = "ROLE_ID")
    )
    private Collection<Role> roles = new HashSet<>();
}

Roles.java

@Entity
@Table(name = "ROLE")
@Builder
@Data
@NoArgsConstructor
@AllArgsConstructor
@EqualsAndHashCode(callSuper = true)
public class Role extends BaseEntity {

    @Column(
            name = "NAME",
            nullable = false,
            unique = true
    )
    private String name;

    @ManyToMany(mappedBy = "roles")
    @JsonIgnore
    private Collection<User> users = new HashSet<>();

}

BaseEntity.java

@MappedSuperclass
public abstract class BaseEntity implements Serializable {

    @Id
    @GeneratedValue(
            generator = "UUID"
    )
    @GenericGenerator(
            name = "UUID",
            strategy = "org.hibernate.id.UUIDGenerator"
    )
    @Column(
            name = "ID",
            updatable = false
    )
    private UUID id;
}

I saw this question many times on stackoverflow. I've tried multiple solutions but none of them worked and i can't seem to find the issue.

Edit: I have no ideas why, but it seems that the issue was coming from the fact that I was using UUID as primary keys. Now that I changed it to long values, it's working properly.