ERRO: inserir ou atualizar na tabela "promos" viola a restrição de chave estrangeira "fk_businesses_promos" [duplicado]

Estou tentando construir uma API REST usando Go e especificamente GORM.

Minhas entidades se parecem com isto:

type Business struct {
    ID        string    `json:"id" gorm:"primaryKey;not null;type:uuid;default:gen_random_uuid()"`
    CreatedAt time.Time `json:"-"`
    UpdatedAt time.Time `json:"-"`

    Email    string `json:"email" gorm:"uniqueIndex;not null;"`
    Password []byte `json:"-"`
    Name     string `json:"name"`

    Promos []Promo `json:"promos" gorm:"foreignKey:CompanyID;constraint:OnUpdate:CASCADE,OnDelete:CASCADE"`
}

type Promo struct {
    PromoID   string    `json:"id" gorm:"primaryKey;not null;type:uuid;default:gen_random_uuid()"`
    CompanyID string    `json:"company_id" gorm:"not null;foreignKey:ID"`
    CreatedAt time.Time `json:"-"`
    UpdatedAt time.Time `json:"-"`

    Target      Target        `json:"target" gorm:"foreignKey:TargetID;constraint:OnUpdate:CASCADE,OnDelete:CASCADE;not null"`
    Active      bool          `json:"-" gorm:"default:true"`
    ActiveFrom  time.Time     `json:"active_from"`
    ActiveUntil time.Time     `json:"active_until"`
    Description string        `json:"description" gorm:"not null"`
    ImageURL    string        `json:"image_url"`
    MaxCount    int           `json:"max_count" gorm:"not null"`
    Mode        string        `json:"mode" gorm:"not null"`
    PromoCommon string        `json:"promo_common"`
    PromoUnique []PromoUnique `json:"promo_unique" gorm:"foreignKey:PromoUniqueID;constraint:OnUpdate:CASCADE,OnDelete:CASCADE"`
}

type PromoUnique struct {
    PromoUniqueID string `json:"-" gorm:"primaryKey;not null;type:uuid;default:gen_random_uuid()"`
    Body          string `json:"-" gorm:"not null"`
    Activated     bool   `json:"-" gorm:"default:false"`
}

type Target struct {
    TargetID   string                `json:"-" gorm:"primaryKey;not null;type:uuid;default:gen_random_uuid()"`
    AgeFrom    int                   `json:"age_from"`
    AgeUntil   int                   `json:"age_until"`
    Country    countries.CountryCode `json:"country"`
    Categories []Category            `json:"categories" gorm:"foreignKey:CategoryID;constraint:OnUpdate:CASCADE,OnDelete:CASCADE"`
}

type Category struct {
    CategoryID string `json:"id" gorm:"primaryKey;not null;type:uuid;default:gen_random_uuid()"`
    TargetID   string `json:"-" gorm:"not null"`
    Name       string `json:"name" gorm:"not null"`
}

O código do meu serviço se parece com isso:

func (s *promoService) Create(ctx context.Context, promoDTO dto.PromoCreate) (*entity.Promo, error) {

    activeFrom, _ := time.Parse("2006-01-02", promoDTO.ActiveFrom)
    activeUntil, _ := time.Parse("2006-01-02", promoDTO.ActiveUntil)
    var categories []entity.Category
    var promoUniques []entity.PromoUnique
    for _, category := range promoDTO.Target.Categories {
        categories = append(categories, entity.Category{
            Name: category,
        })
    }
    for _, promoUnique := range promoDTO.PromoUnique {
        promoUniques = append(promoUniques, entity.PromoUnique{
            Body: promoUnique,
        })
    }

    company, _ := s.businessStorage.GetByID(ctx, promoDTO.CompanyID)

    promo := entity.Promo{
        Target: entity.Target{
            AgeFrom:    promoDTO.Target.AgeFrom,
            AgeUntil:   promoDTO.Target.AgeUntil,
            Country:    countries.ByName(strings.ToUpper(promoDTO.Target.Country)),
            Categories: categories,
        },
        CompanyID:   company.ID,
        Active:      true,
        ActiveFrom:  activeFrom,
        ActiveUntil: activeUntil,
        Description: promoDTO.Description,
        ImageURL:    promoDTO.ImageURL,
        MaxCount:    promoDTO.MaxCount,
        Mode:        promoDTO.Mode,
        PromoCommon: promoDTO.PromoCommon,
        PromoUnique: promoUniques,
    }

    company.Promos = append(company.Promos, promo)
    _, err := s.businessStorage.Update(ctx, company)
    if err != nil {
        return nil, err
    }

    return s.promoStorage.Create(ctx, promo)
}

Meu armazenamento se parece com isso:

// Create is a method to create a new Promo in database.
func (s *promoStorage) Create(ctx context.Context, promo entity.Promo) (*entity.Promo, error) {
    err := s.db.Model(&promo).WithContext(ctx).Create(&promo).Error
    return &promo, err
}

Mas quando tento alcançar um ponto final recebo este erro:

/opt/internal/adapters/database/postgres/promo.go:22 ERROR: insert or update on table "promos" violates foreign key constraint "fk_businesses_promos" (SQLSTATE 23503)       

O que devo fazer? Pesquisei algumas outras perguntas no stackoverflow com o mesmo problema, mas nenhuma me ajudou.