Async `loadfile` IPC command does not return anything

mpv Information

I downloaded the latest winbuild version from here: https://github.com/zhongfly/mpv-winbuild/releases/tag/2025-07-16-440f35a

The --version flag doesn't print anything (?).

Other Information

- Windows version: Microsoft Windows [Version 10.0.22621.1344]
- GPU model, driver and version: Intel N100 UHD Graphics
- Source of mpv: https://github.com/zhongfly/mpv-winbuild
- Latest known working version: -
- Issue started after the following happened: -

Reproduction Steps

1. Start mpv with the --input-ipc-server=pipe flag
2. Connect to the IPC server
3. Send a loadfile command with async set to true
4. No response

Expected Behavior

The player returns a JSON like {"request_id":0,"error":"success","data":{"playlist_entry_id":1}}.

Actual Behavior

The player does not return anything, even though the command succeeds (the new file loads).

Log File

output.txt

Sample Files

No response

I carefully read all instruction and confirm that I did the following:

• I tested with the latest mpv version to validate that the issue is not already fixed.
• I provided all required information including system and mpv version.
• I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of --log-file=output.txt.
• I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
• I attached the full, untruncated log file.
• I attached the backtrace in the case of a crash.

Reproduce the async loadfile request through mpv's IPC server using the steps in the issue, and inspect the attached output.txt log. The work is done when a successful request returns the expected JSON response containing the playlist entry ID.