This is my main model definition:

const Sequelize = require('sequelize') 

// Import sequelize object,  
// Database connection pool managed by Sequelize. 
const sequelize = require('./database.js') 

const CartTransaction = require('./CartTransaction');
const PayPalOrder = require('./PayPalOrder')

const CartTransactionPayPal = sequelize.define('cart_transaction_paypal', {

cart_transaction_paypal_id: {

    type:Sequelize.INTEGER, 

    // To increment user_id automatically. 
    autoIncrement:true, 
    allowNull:false, 
    primaryKey:true
}, 

status: {type: Sequelize.STRING, allowNull: false}

});

CartTransactionPayPal.belongsTo(CartTransaction, {as: 'paypal_transactions', foreignKey: 'cart_transaction_id'});
CartTransaction.hasOne(CartTransactionPayPal, {as: 'paypal_transactions', foreignKey: 'cart_transaction_id'});

CartTransactionPayPal.belongsTo(PayPalOrder, {as: 'paypal_orders', foreignKey: 'paypal_order_id'})
PayPalOrder.hasOne(CartTransactionPayPal, {as: 'paypal_orders', foreignKey: 'paypal_order_id'})

When I attempt to do this joining operation:

await PayPalOrder.findAll({
        include: [{
            model: CartTransactionPayPal,
            as: 'paypal_orders',
            required: true,
            include: [{
                model: CartTransaction,
                as: 'paypal_transactions',
                required: true

I get this error:

"Unknown column 'paypal_transactions.cart_transaction_id' in 'field list'",

Why is this happening though. Shouldnt it be joining CartTransactionPayPal on CartTransaction since its a nested include? Am I missing something? Is my syntax wrong for nested include statements?