I am having the identical issue. I am using Studio One Pro 5.0.0 with Windows 10. When I select a Presence patch, say "Oohs", it sounds and plays great. Then I close the song file and get out of Studio One. Next time I open the song, Presence still indicates that the "Oohs" patch is selected, but the envelopes have changed, and all I hear is the initial attack portion of the sound, with no sustain. But if I then go in and re-select the "Oohs" patch, it loads the correct envelopes and settings, and it sounds fine again. Seems to me like maybe Studio One is incorrectly initializing the selected Presence patches when loading the song file.
Anyway, I sure hope you folks at PreSonus can find a solution!