My assumption this would have something to do with ARPs - one function scene buttons can serve (shortcuts for changing arps). I loaded "The Frog" and switched between scene 1 and 2. Scene 1 doesn't have drums and scene 2 does.

All I could notice that may fit the bucket of "not smooth" is that when switching from scene 1 to scene 2 - the drums do not start right away depending on where within the measure you switch.

Since this seemed isolated to only the drums - I touched the drum Part, clicked "common" and chose the arpeggio menu. There's a setting for the ARP to align to the measure or real-time. Here, the ARP was set to "measure". Therefore, when the ARP is changed for the drums - the new ARP will wait until the next measure to start. And when scene 1 sounds like Mute 4/4 (drums off - I didn't check, but imagine it's something like this) and scene 2 has some drum ARP active - this "measure" setting is what enforces the timing.

To me, rather than having to line up your own playing to the measure - the benefit of this system is that the ARP itself will only change the drum pattern (or start the pattern) on full measure boundaries which, as I see it, actually relaxes the dependency of your hitting the scene buttons exactly on time.

All that said - if you'd rather not have the drums wait - then change the setting to "real time" instead of "measure" for the drum ARP. Now "poof" - the drums start right when you press the button no matter where you are within the measure when you press the scene button.

Like so many other things - there's a certain degree of "digging" that is encouraged so you work to discover what the parameters do and match what you hear with parameters. The presets offer good examples and also "fun" challenges to figure out why say the scene buttons work like they do.

@Jason, in that preset, the Sync Quantize is off. I put this to 480, and it seemed to solve it for me. But I'm not sure this is doing anything. It might just be I couldn't get it wrong the right way after.

Do you know much about Sync Quantize? I always turn it on, and almost always at 480, and this has always worked for me... but I'm just an arpist, so could be delusional.

Thanks Jason I appreciate your help. That answered my question completely. Still in the new phase as I got my MODX in August so still learning about the deeper levels of programming.