[5.x]: "Add a Product" button not appearing on the product relationship modal

[ax2000]

What happened?

Description

I'm not sure if I'm missing anything or this is the intended behaviour but when clicking on the Add a product button in my Commerce Products relationship field that is restricted to a single source, I am unable to create a product inline from the modal (No Add a product button appearing on the bottom left of the modal)

I have several Entries relation fields in that same section and they all show a Add an entry button on the bottom left of the modal that allows me to create new entries on the go and I was expecting the same behaviour with Products relationships.

Steps to reproduce

1. Create New Commerce products field restricted to a specific source
2. Click on the Add a product button on the form
3. The modal lists existing products but no Add a product button appears in the modal

Craft CMS version

5.8.22

Craft Commerce version

5.5.2

PHP version

8.3.27

Operating system and version

Linux 6.10.14-linuxkit

Database type and version

MySQL 8.0.40

Image driver and version

Imagick 3.8.0 (ImageMagick 6.9.11-60)

Installed plugins and versions

Amazon S3 2.2.4
Button Box 5.0.1
Campaign 3.8.1
CKEditor 4.11.0
Control Panel CSS 3.0.0
Control Panel Nav 5.0.5
Craft Commerce 5.5.2
Do It Yourself widget 4.1.1
Expanded Singles 3.0.3
Feed Me 6.11.0
Field Manager 4.0.3
Formie 3.1.8
Guest Entries 4.0.1
Hyper 2.2.11
Mailgun 3.1.0
Patrol 6.0.1
QRCode 3.0.0
Scout 5.0.7
Smith 3.1.1
Snaptcha 5.1.2
Sprig 3.7.1
Stripe for Craft Commerce 5.1.0.1
Super PDF 5.0.4
Table Maker 5.0.6
Timber 2.0.4
Twigpack 5.0.0

[linear]

COM-513