I do this thing in my sequencer where I convert MIDI note events to frequencies. Only, I forgot about this, and I didn’t use good naming, so the sequencer was calling the frequencies “note” too.

Then I went to create a sequencer event using “note” and put in 63 (a middle pitch MIDI note) and wondered why nothing was playing. Answer: Those sampled patches did not want to play at 63hz. Duh…