Take a look at these two threads, they may prove useful in understanding what might be going on. They don’t provide a solution sadly, and I too found serious issues trying to use the Polyend Synth as a simple three instrument multitimbral device sequenced from an external DAW (in my case Ableton), which Polyend really needs to fix soon as it’s been a known issue for at least a year or more, as evidenced by these threads.