I have just upgraded my MS-1 mk1 to the new firmware (1.1.14) and it seems the new "Last" note priority option has some weird behaviour. With the envelope switch in "GATE" or "LFO", when you release a note that is not the most recently played note, it jumps to sounding whatever is the lowest currently held note, even though you have still not released the most recently played note. For example, if you hold C, hold E (above), hold D (in the middle), then release E, it sounds the C again, even though the last played note D still has its key held down so should still be sounding.
I don't know whether the mk2 currently has the same issue or not, as I only have the mk1.
I did spot one unannounced improvement in the new firmware. With older firmware if you used MS-1 as a midi keyboard via USB or DIN, to control other synths, it was easy to get stuck notes, because if you played chords with both hands fairly fast it could get overloaded and send a note off message before the corresponding note on message for that key had been sent. I don't think that issue is happening anymore, with this new firmware.