i am on osx 10.11 , playing the midi file directly to the preenfm usb via ableton live.
but it also happens with my midi controller (without any computer involved, direct midi-din connection)
i therefore don't think it is a daw specific issue. note that most daws (e.g. ableton live) send an all note off event when you stop the clip.
so it may be hard to hear. (best to make the clip longer and let it run some more after the last note has played)
i use the overclocked firmware 2.03o but i tried the non overclocked version 2.03 as well and it still happens.
my midi controller works fine with multiple other hardware and software synths, so i can rule that out as well.
i use the preenfm in multitimbral mode, all 4 channels have loaded the same preset, because my controller sends on 4 channels, it is much like a bass guitar, but midi. presets are all mono. i have tried a bunch of the dx7 presets, i'm sure it happens on the first preset from the dx7 set, i just adjusted it to be mono, with some glide and aftertouch going to im*. i then loaded this preset into all four instrument slots. not all channels get stuck at the same time, if i just play on one channel, only that one will have a stuck note, so there is no crosstalk or something... my preenfm2 is not at my home atm, so i cannot check if it happens with all presets but i am sure it was more then one.
thanks for looking into it. would it help if i post the exact settings of a sound where it happens?