[5.x]: Products of completed order not added to committed inventory

[MatthiasBrodelet]

What happened?

Description

In our production site we noticed that when 2 different customers bought the same product it did not add those to the committed inventory.
Now we are stuck because we can’t force it to the committed inventory after the order has already been completed.
This means we can’t fulfil it.
The button at the top right is not visible on the order detail page.

I did a test to see if I can reproduce the issue locally with a dump of the database but that is not the case.
When I create my order it gets added to the committed inventory as expected.

I guess we don't have enough info to pinpoint where exactly the bug is located but it would be nice to have a way to fix this so we can fulfil the orders.

I tried removing the line item and adding a new one but for some reason it does not matter how many new products I add to the order. I can never fulfil them.
But that may be a whole different error because when I create a new manual order and change the quantity from 1 to 2 after completion the fulfilment amount is not adjusted. It stays on 1.
This last bit is 100% reproducible.
Notice the quantity '2' in the background and the fulfilment amount in the modal.

EDIT: I figured out that this product variant did not have the "inventory" enabled at the time of the 2 orders. Our client did activate it in between the placement of the orders and notifying us that the fulfilment did not work.
That explains the biggest issue.

Is there a logical explanation as to why it does not add more products to the committed inventory after upping the quantity in the order?

Craft CMS version

Craft Pro 5.4.8

Craft Commerce version

5.2.0

PHP version

8.2

Operating system and version

No response

Database type and version

No response

Image driver and version

No response

Installed plugins and versions

[linear]

PT-2268 [5.x]: Products of completed order not added to committed inventory