As a new user still getting to grips with the basics of Reaper, I've come across a bewildering annoyance when interfacing with my TR-8S. With MIDI clock enabled for the TR-8S's output (Preferences > Audio > MIDI Devices), opening any project changes the device's internal tempo to it's maximum of 300 BPM. This seems to happen with any permutation of the TR-8S's sync/tempo settings, and in some cases also modifies the active pattern's saved tempo (which is used when TempoSrc is set to PTN). None of this happened with Cakewalk, which is the only other DAW I've used the TR-8S with.
The pattern does play according to the project tempo when sync is set to USB (and the tempo LCD goes blank as usual), but having to turn the tempo knob around several full rotations just to return to in-box editing/jamming is an unwelcome fuss that breaks my workflow.
As far as I can tell, the brief MIDI implementation chart provided by Roland is of no use here, since there is no entry for a MIDI message that would edit the tempo setting. I can come up with two scenarios: either Reaper's MIDI clock differs from Cakewalk in some way that the TR-8S responds to in an undefined manner, or Reaper is sending something else in addition to MIDI clock that is triggering some undocumented MIDI functionality in the TR-8S. Or perhaps I'm just missing something obvious.
Here's a gif showing exactly what happens when I open a project:
https://photos.app.goo.gl/YaP8hsUvbb7pZmSH8
My MIDI preferences on Reaper:
https://photos.app.goo.gl/VrqBJgN8TYKwAxYY7
Screenshots from the TR-8S reference guide showing the pertinent settings:
https://photos.app.goo.gl/nxQ4V5hsLjd5C3iP6 &
https://photos.app.goo.gl/iZm7ZU8rQuapMxa66
The MIDI implementation chart is also attached.
Any help would be much appreciated!
———EDIT———
I seem to have found a solution. The device shows up as two different interfaces, one simply called "TR-8S" and the other "TR-8S CTRL". Sending MIDI clock to both outputs simultaneously stops the issue from occuring. I have no idea why though, since there is no documentation for these separate interfaces, and thus far I had only discovered that the latter sends and responds to kit changes.