[BUG]: Inter-application MIDI no longer received after receiving app is closed and reopened a few times

Windows Version

Windows 11 Pro 25H2

Service Installation Method

Other (please indicate below)

SDK version, if appropriate

GitHub Preview SDK Release Candidate 2 - 1.0.15-rc.2.18 (x64)

Location

Application using WinMM MIDI 1.0 (Classic API)

Type of bug

Cannot receive messages from MIDI 1.0 device

Steps to reproduce

Open Haken Editor (any recent beta version, I'm currently on 10.72) and the instrument it controls, such as a Haken Continuum or Haken ContinuuMini, ensuring that they are communicating with each other.

Configure Haken Editor's Ext 1 Output to send all data to a MIDI device that can be monitored by another application, if it is not already. The MIDI device could be a virtual MIDI port, a Windows MIDI Services loopback endpoint or a port of an external MIDI router such as an iConnectivity mio.

Close the editor.

Open Mido-Ox or another MIDI monitoring application and connect it to the destination MIDI device to which the editor's Ext 1 will be sending when reopened.

Reopen the editor.
If all is well, the MIDI monitor shows the traffic both ways between the editor and the instrument. As the editor and instrument exchange heartbeats when idling, the traffic should never stop for more than a second.

While keeping the editor open and connected to the instrument, close and reopen the MIDI monitor a few times. Each time, check to see if it still shows MIDI traffic.

Actual result

The third and subsequent times the the MIDI monitor is reopened, no MIDI is received. Yet the editor and instrument are still communicating with each other.

Expected behavior

Every time the MIDI monitor is reopened, it should show the current MIDI traffic between the editor and the instrument.

Additional notes

I hesitated to post a WMS bug, as I only have one sender application to try this with. But Haken Audio are reluctant to spend time investigating this at the moment, as Windows MIDI is undergoing a major change. I agree with their assessment thar it's probably a Windows MIDI problem, in which case there might not be anything that could be done about it at the Haken Editor end. Also, the impact on users is likely to be minor, and there's an easy workaround (see below). So I thought I should report it here. I understand you have a ContinuuMini with which the problem might be reproduced.

I don't think the problem can happen if Haken Editor is opened before the MIDI monitor. If it can, it seems to be much more likely to happen if the MIDI monitor is opened first, as described in Steps to Reproduce above.

I noticed the problem when testing an application I'm developing, PitchGrid-Continuum Bridge. But I'm able to reproduce it with Midi-Ox.

Workaround

In Haken Editor, reselect the output under the Ext Device menu, even though it already shows itself as connected.