Midi effects not working

I add the midi pattern plugin to zynaddsubfx, but I get not pattern,
same problem with arpeggiator and some other plugins.
Creating a seperate midi track with the arpeggiator plugin and routing this to another channel works with the arpeggiator plugin, but not with the pattern plugin.

I don’t find other people with this issue. What’s going wrong here?

Arpegiator works for me. I couldn’t find any documentation on how the MIDI Pattern plugin is supposed to work. The original writer does not reference it on their own website.

[Edit] I have MIDI Pattern working too. It seem to work thus: You set the velocity of each step and then each sequential note played will play at that velocity, e.g. set pattern length to 4, notes 1 & 3 to 100 and notes 2 & 4 to 50 then the first note played will sound at vel 100, next at 50, etc. Setting Sync to “By note” will make it behave this way. Setting to “By host clock” will only work when sequencer is playing and will advance the step based on the “Divisions” setting.