when playing a noteblock it sometimes doesn't output particles!

I checked my particles and it was on ALL/MAXIMUM
1: I put TWO noteblocks down SAME PITCH (one space gap)
2: I put a redstone torch down in between them.
3: I repeated these steps 20 times or so.
4: one time it showed the note particle on both, the other time only on one of them. and sometimes it didnt even show particles on neither one of them.

5: check the attachment
6: fix the bug! please!