[5.x]: Switching the propagation method for matrix fields does not propagate update existing contents

[MoritzLost]

What happened?

Description

Just ran into this in the latest version, this used to work correctly some versions ago. Entries that should be propagated to all sites after switching the propagation method don't do so.

Steps to reproduce

1. Create a matrix field and set the propagation method to Only save entries to the site they were created in. Add it to an entry type used in a section that's enabled in multiple sites and propagated to all sites. Create an entry and add an entry in the matrix field in one site, but not the others.
2. Change the propagation method to Save entries to all sites the owner element is saved in and wait for the resulting queue job to finish.
3. Check the entry in multiple languages. The existing entry in the matrix field has not propagated.
4. Save the (main) entry, still no propagation.
5. Edit the entry in the matrix block and save again, now the entry is finally propagated.

Expected behavior

The matrix entry should propagate to all sites as soon as I change the propagation method.

Actual behavior

The matrix entry does not propagate, neither on changing the field nor on saving the main entry, resulting in inconsistent behaviour.

Craft CMS version

5.7.4

PHP version

8.3

Operating system and version

No response

Database type and version

No response

Image driver and version

No response

Installed plugins and versions

[i-just]

Hi, thanks for reporting! I raised a PR for this.