UPDATE: I read your other post. The Axe-Fx Metronome cannot be synced via cc. It is free running. But with Live, couldn't you just create a metronome track and route it to your ears (or whatever)? As for tempos fluctuating, this is inherent to the way MIDI beat clock works. A downstream device watches the constant pulse. Have you considered instead sending a stream of CC#14 pulses when you need to change or set tempo? Did you know you can also address tempo directly by sending a SysEx message to the Axe-Fx? It isn't documented, but you could snoop on Axe-Edit to find those bytes...
Thanks.
I'm not even trying to sync LFO's or anything very fancy. I just want the down beats in the Axe/Metronome to align to the MIDI clock of the system providing timing. For me (others have other issues) the main issue is that I (and our singer/2nd guitarist) frequently use the flashing tap-tempo light on the MFC or the the Axe as a tempo indicator when starting a song. This has been very handy in the past. But now, I'm working on adding a laptop running Ableton to trigger backing tracks here and there. I'm running a click track from Ableton over to the drummer (in place of his stand-alone metronome). So far so good. But now, for these songs that I or the other guitar player start: since the Axe doesn't sync its metronome ON-BEAT, the flashing tap-tempo light on my MFC becomes useless as a visual indicator of the down beats. If we had in-ear monitors I'd run a click into them, but we don't, and won't have the finances to do so anytime soon. (It's a easier and less expensive for a stationary drummer to stick in some not-too-expensive wired earphones than it is for a standing, moving guitar player/singer.
Maybe there are other solutions, such as having the drummer give us soft stick-clicks, or wave a drum stick like a conductor's batton. I just figured I wouldn't lose the handy function of the flashing MFC LED as a visual metronome. I figured this nearly $4000 combination of gear (Axe+MFC) would handle syncing to MIDI clock like far lesser equipment has been capable of for decades.
Note: this also means one can't align the looper with the rest of the system (Live, hardware, etc). I know you're saying - use Ableton if you want a looper! And yes, that's one option, but I only use the looper once, in the last bit of a song, so adding yet more complexity and cabling and potential failure points doesn't seem like the most optimal solution. I think the Axe should be capable of aligning to MIDI clock! I really don't think that's unreasonale to expect.
As far as sending CC#14 or SysEx for setting tempo, for me, setting the bpm isn't the issue - I have one patch per song, and the bpm is already set for each song. The issue is the Axe not being aligned with the beat, and the problems this causes with the flashing tempo light, looper, and LFOs (for those trying to sync them). As you said
The Axe-Fx Metronome cannot be synced via cc. <<<--- That right there, that IS the problem. One that I, and others, wish Fractal would address.