Nebulae V2 doesn't clear the buffer properly

Hi everyone, lately I’ve noticed that my nebulae when used in granular mode with live audio is unable to completely clear the buffer.
After clearing the buffer if I record something new, a small portion of the old audio buffer is still audible, just a few small grains usually.
I have already re-installed the firmware, the problem seemed solved but after a few days it started again… I don’t know, maybe I’m doing something wrong.