Opencart: [v3.0.3.2] sale/order/add - bugs when adding a new order or edit existing order

[Li-Yen]

What version of OpenCart are you reporting this for?
3.0.3.2

Describe the bug
sale/order/add - When I try to add a product to the manual order insertion (Step 2), the product is not showing up on the product list table.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Sales / Orders'
2. Click on 'Add New'
3. Fill up _1. Customer Details_ and press Continue button
4. On _2. Products_, Choose Product and then click 'Add Product'

5. Scroll to see the order / product list, the product is not appended on the table. (This error also occur when I try to edit the order that submitted by customers on the Admin dashboard).

1. Click 'Continue', fill in _3. Payment Details_, then click 'Continue.
2. On _4. Shipping Details_, fill up the info and click 'Continue'.
   

   8. On _5. Totals_, the dropdown box for Shipping Method is disabled.

Expected behavior

• The new product that I choose to add on the order should appear on the order/product list.
• The dropdown list should be enabled for admin to select Shipping Method for that new order.

Screenshots / Screen recordings
https://drive.google.com/file/d/16YAmblyBdzYXGxiqYEspdlEh4FgjTKhR/view

Server / Test environment (please complete the following information):

• Local development? Deployed to a web server?
• Operating system: linux
• PHP version: 5.6.29
• Apache version: 2.4.25
• Kernel Version: 2.6.32-896.16.1.lve1.4.51.el6.x86_64
• Browser(s) tested with Chrome (Version 75.0.3770.100 (Official Build) (64-bit))

Additional context
This problem happens during Add new Order / Edit Order on Admin dashboard. Need to get this fix asap.

[Li-Yen]

wonder if anyone discover the same issue?

[straightlight]

PHP version should be upgraded to at least 7.2.4 or above. As for the rest of the troubleshooting, use the developers kit and see from the console tab if errors do appear during the evaluation on what you described on the above.

[jeffreyeng-opencart]

I have tested with process and I have no problem. I have agree with straightlight that you need to try and upgrade your environment and see if the problem persist or not. I'm going to closed this issue. If you think this persist, then re-open this issue.