Hi Ben, sorry I'm late on this one... I haven't as yet had a proper play with an LP2, so I've no idea at all how the MIDI is implemented, or what it's set up to control... I know that the LP1 had some problems syncing externally - it's not a part of the functionality I've experimented with much...
what you might want to try is putting them in series, and looping from one to the other, so you do a short loop on the first looper in the chain, and then play a longer phrase over the top, looping that and the loop together into the other looper. You can then either stop the first loop and do something else with that pedal, or mess around with it (play it backwards, slice it up, do all those weird things the LP2 is capable of to it
As an example - other than the internal sync on the LP1, there's no looper sync on new album, but there are a couple of moments, most notably on the last track, where I loop what Daniel is playing so we stay in sync (the main drum groove is looped with the bass part, and then we both play over the top... it gets tricky to tell who's doing what