[BUG] WinMM app stops receiving messages.

[m-komo]

Describe the bug

This issue was observed with the Internal Preview (2025-02-18 Customer Preview 2 Daily).

WinMM app stops receiving messages.
This issue can be reproduced with both MIDI 1.0 device and MIDI 2.0 device regardless of the driver.

To Reproduce
Following steps may not be required steps but they are reproducible steps.

1. Set the Roland UM-ONE mk2 to class-compliant mode (set the switch to "TAB") and short INPUPT and OUTPUT to loop back messages.
2. Attach the UM-ONE to PC.
3. Open the Pocket MIDI and choose the "UM-ONE" as an InputPort and an OutputPort.
4. From the "File" menu, open the attached "test.pocketmidi" file.
5. Open midi.exe and monitor the "UM-ONE".
6. Open midi1monitor.exe and monitor the "UM-ONE".
7. In the two System Exclusive windows, click the "Transmit" buttons to send messages.

8. Close the Pocket MIDI.
9. Open midi.exe and send 0x20904040 to the UM-ONE to make sure both monitors still working.
10. Double click the attached "test.pocketmidi" file and click the "Transmit" button on the System Exclusive windows.

The midi1monitor.exe does not receive any messages.

Expected behavior
The midi1monitor.exe continues receiving messages.

Installer Name or Version

• [Internal Preview] Windows MIDI Services (In-Box Service) 1.0.3-preview-11.250218-1656-x64.exe
• [Internal Preview] Windows MIDI Services (SDK Runtime and Tools) 1.0.3-preview-11.250218-1656-x64.exe

Desktop (please complete the following information):

• OS: Windows 11 24H2 build 27788.1000 (Insider Canary channel)

Device information, if this is with an external MIDI device:

• Roland UM-ONE mk2

Application Information

• MORSON Pocket MIDI (64bit MME MID app)
  https://www.morson.jp/pocketmidi-webpage/

[Psychlist1972]

FYI. I cannot repro this on 1.0.3-preview-11.250228-139 which I plan to release later today.

Both midi1monitor and midi.exe receive all sent messages. I tried clicking on them in different orders, but the messages still got through.

[m-komo]

@Psychlist1972 Thank you for your prompt response.
I will check this with the next release.