Hi @Yo-chan,
you know…I also use voicemeeter…I have experienced this particular kind of noise when Cantabile and Voicemeeter get out of sync with each other. When this happens, switching the audio engine on and off (maybe a few times) can be of help. I usually do it in Cantabile, but in your case, since Cantabile is minimized, I would try to do it in Voicemeeter.
I also suggest to try without Voicemeeter, connecting Cantabile directly to the ASIO driver of your interface, to check if it happens anyway.
However, if this is actually the issue, I can’t see a direct connection with the buffer length. 
Cheers!
Gabriel
Edit: As soon as I get to my music PC, I will check if it happens also on my system.
Update: no, it does not happen in my system. Unfortunately, I am not able to reproduce the problem.