"flush-regions-on-save: true" is not working

[alandamore]

Expected behavior

Edit config\paper-world-defaults.yml
Change flush-regions-on-save: from "false" to "true", restart server.
I expect to see regions with changed blocks to be written to disk when the autosave (default every 5 mins) happens.

Observed/Actual behavior

Region files are not updated on the hard drive. The timestamp doesn't alter. When using Bluemap it never decides to trigger an update. Extra info: A server command "save-all" does not save regions. "save-all flush" does save to disk (and then Bluemap sees the change).

Steps/models to reproduce

I'm using Windows 10 Pro 22H2, and Amazon Coretto - "java -version" gives "openjdk version "21.0.4" 2024-07-16 LTS".

1. Start a brand new, default paper server, no flags, no plugins, accept EULA:
   java.exe -jar paper-1.21.1-45.jar

2. Connect a client, break some blocks, disconnect.

3. Stop the server to force regions to be written to disk.

4. Edit config\paper-world-defaults.yml: Change flush-regions-on-save: from "false" to "true", save file.

5. Restart server.

6. Connect client, break some blocks...

7. Observe the files in \world\region, they do not get updated unless a "save-all flush" is issued.

(Yes, I waited a long time [many minutes] and also tried with "bukkit.yml" "autosave:" changed from 6000 to 1200 to try to hurry it up...)

Plugin and Datapack List

No plugins, default "bare bones" paper installation
There are 3 data pack(s) enabled: [vanilla (built-in)], [file/bukkit (world)], [paper (built-in)]

Paper version

This server is running Paper version 1.21.1-45-master@5b2c43e (2024-08-25T18:01:51Z) (Implementing API version 1.21.1-R0.1-SNAPSHOT)
You are running the latest version

Other

No response

[electronicboy]

https://docs.papermc.io/paper/reference/system-properties#paperenable-sync-chunk-writes

[electronicboy]

that config option is apparently no longer wired up in the new chunk system? @Spottedleaf

[electronicboy]

The issue was re-opened awaiting comment from leaf, that system property should enable the option in server.properties; if that doesn't work, that would be on leaf