[BUG]: Realtime/Clock to device sends seemingly random things
@Psychlist1972 is already working on this.
Since Feb 15, 2026.
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Description
Windows Version
25h2 retail
Service Installation Method
Other (please indicate below)
SDK version, if appropriate
No response
Location
Application using WinMM MIDI 1.0 (Classic API)
Type of bug
MIDI messages corrupted
Steps to reproduce
First off: i have two machines (both 25h2). One (Desktop-PC) with Midi Services deployed via Windows Update, the second (a Laptop) has not yet received it - and I also stopped updates for the time being, until it is fixed.
The following issue is only happening on my Desktop PC. The Laptop with the old Midi stack does not have the issue.
I have my Arturia Keystep plugged in and configured (in Reaper) to receive Midi Clock. However, the clock that arrives does not make sense. It randomly jumps between 26bpm and 560bpm, while the song is actually in 110bpm. Also, the Keystep randomly stops even though Reaper is still going and therefore hasn't sent the Midi Stop message.
The same project on the Laptop runs fine and the Keystep gets the correct clock.
Expected behavior
The clock should transmit the correct bpm.
Additional notes
No response
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