I wanted to send clock to another MIDI device, but the KSP was sending all midi from channels, and I didn't want that. So I disabled all the midi outs from all the channels. Channels with midi out disabled started to skip notes randomly, while running an arp. Others would send a gate out when you release a key. Or the pitch Cv would become stuck, or maybe just completely wrong.
All this CV weirdness happened after disabling the MIDI out. And stopped happening when I set all the MIDI outs to ON again (sent them all to channel 16, which I can then filter in the other device).
looks like a bug.