The MX has the LFO set to Loop, Tempo Sync is On, Key On Reset is 1st On (I've tried the others to no avail), Hold is On, MIDI Sync is Auto

KEY ON RESET brings your musical expertise into the mix. The LFO will re-start when you touch the keyboard because you have instructed to reset when you turn the first Key On. If you’re late or early, the LFO will run at the external tempo but offset by your being early or late.

Much like arpeggiators, you can Sync the clock, but if you miss the downbeat, your Arp will be in tempo, but shifted before or after the beat by the amount you are early or late.

So there is a musical accuracy that is necessary to pull this off, in addition to making the settings. If you are using an MX Rhythm Pattern w/Sync start (hold Stop and tap Play) or use a DAW, to insure when exactly the Key On is sent to the MX. This will guarantee the accuracy of the KeyOn event.

Next, you need to understand the shape of the LFO, example: if you are using an LFO Wave shape that starts at zero and rises (triangle wave) and the Phase is 0 degrees, if opening a filter, the filter will fully open (reach the apex) behind the beat. You may need to offset the Phase 90 degrees so that *fully open* occurs musically where you require it. I don’t recall Phase Offset as a programmable feature on the MX so you are best to create your own USER LFO that outlines what/where you want the fully open point.

I can’t say that I have worked much with the LFO on the MX, but those are the things you must take into account. Currently, my MX is not in my studio so I cannot verify my recollections (at this time)...