Sounds like a bug to me - I’ve never seen an arp behave this way - what’s the musical benefit? It’s supposed to play a chord, not a note and a chord - I think that’s what the last release notes implied, that the new mode was to support poly(clues in the name).
Also, it behaves the same sequenced - plays at least one single note and then chords.
“that’s the way it is” ( not a bug) - it’s a #manmachineinterface
