Fixed nested element deletion bugs

[brandonkelly]

Scenario 1

Setup

• Matrix field “Sections”, in Cards view
  • Matrix field “Containers”, in Blocks view
    • Matrix field “Text”, in Blocks view
      • Plain Text field

Steps to Reproduce

1. Create an entry with one Sections nested entry, with two Containers nested entries, each with one Text nested entry, with their Plain Text fields filled in.
2. Fully save.
3. Open the Sections nested entry slideout, and edit the first Plain Text field. Then press Save on the slideout. Repeat two more times.
4. Open the slideout a 4th time. The second Container nested entry will be missing.

Scenario 2

Setup

• Matrix field “Sections”, in Cards view
  • Matrix field “Text”, in Blocks view
    • Plain Text field

Steps to Reproduce

1. Create an entry with one Sections nested entry, with two Text nested entries, with their Plain Text fields filled in.
2. Fully save.
3. Open the Sections nested entry slideout, and edit the first Text nested entry’s Plain Text field. Press Save on the slideout.
4. Open the Sections nested entry slideout, and edit the second Text nested entry’s Plain Text field. Press Save on the slideout.
5. Discard the root entry’s changes.
6. Open the slideout. The first nested Text entry will be missing.

Related Issues

• [5.x]: Changes to deeply-nested entries are lost when their owner is edited and saved multiple times #18624