[5.x]: Modified matrix entries don't get updated after adding or deleting an entry to the matrix

[Liamm3]

What happened?

Description

We use a matrix field as our content builder. When we edit an existing entry in the matrix, then add a new one or delete an existing one and then save the entry, all changes are lost.

Steps to reproduce

1. Create a new matrix field

2. Add some entry types (e.g. 'Plain Text')

3. Add the matrix field to a section

4. Create a new entry in the section

5. Add an entry to the matrix

6. Save the entry using Ctrl+S

7. Modify the created entry

8. Add a new entry to the matrix
   

9. Save again

10. All the changes are lost
    

Expected behavior

The modified matrix entry should be saved after saving the entry.

Actual behavior

Changes on a modified entry are lost, after adding a new entry to the matrix.

Craft CMS version

5.1.6

PHP version

8.3

Operating system and version

Linux

Database type and version

MariaDB 10.6

Image driver and version

No response

Installed plugins and versions

• CKEditor 4.0.6
• Dumper 5.0.1
• SEO v5.0.0-rc2

[i-just]

Hi, thanks for reporting. I was able to replicate this if the autosaving of e.g. the text change wasn’t processed before adding a new entry. If you were to wait until after autosaving is done, all the changes would save correctly. I raised a PR for this.

[brandonkelly]

Craft 5.1.8 is out with that fix. Thanks again!