The Bass and Chord channels are "monophonic" with last "key" priority. The Drum and Lead channels are "polyphonic" with 8 "key" polyphony." I put "key" in parentheses because that's the term that's usually used, but "keys" in this context is really pads. I put "monophonic" and "polyphonic" in parentheses because both the Bass and the chord channels can be programmed to play more than one note when you press one pad. They can both play synthesized sounds using two independent oscillators that can play in different octaves and be detuned. They can both play sampled sounds. And, the Chord channel can be programmed to play chords consisting of up to four (at least?) different notes with a single pad press. So, technically, you can play more than one note at a time in the Bass channel, but only one pad press event can be triggered in any time slot. You can see how priority works by pressing and holding one pad in the Bass or Chord setting and then pressing another and releasing it. When you press the second pad, you will hear the notes that it produces. When you let go of the second pad, you will hear the first one, but not both at the same time. Think of sequencing as recording "key" (pad) presses not sounds being generated. The Octave control doesn't generate new sounds. It extends the keyboard (pad board). So, when you sequence one of the "monophonic" modes and layer over them, new pad presses will override earlier pad presses, even in a different object, exactly in the same way that new KEY presses will override earlier key presses if you're layering MIDI or playing back with MIDI on a traditional MIDI mono keyboard synth. This works exactly the same way.
The Drum and Lead section are 8 "key" (pad) polyphonic, so you can layer up to 8 sounds on top of each other while playing or layering in a loop.
Artiphon made these choices of polyphony for good musical reasons that make sense if you think about them. There are tricks that you can do with monophonic synths that work well on the Orba, so you should think of this as a strength rather than a weakness. If all you want is a truly polyphonic bass, you can use the Lead mode and drop it down up to three octaves. Some of the leads sounds actually make pretty good bass sounds when you drop them down some octaves.
Also, the Bass section is intended to play an entire scale. The lead section is intended to play pentatonic scales - again for good musical reasons.
PS: the firmware is up to date (after lots of trial and error with the Windows App), and this Orba 2 seems to have other issues like the well known "having to spam the power button for five minutes because it doesn't wanna turn on after sitting around for a while" song and dance.
mcSp00ks
So I go into bass mode, record a small loop. Still in base mode, switch octave and try to add more bass to the current loop. Upon doing so, the previously recorded notes interfere with the ones I'm trying to play currently or get removed when I play new notes at the same exact time. The new bass notes just do not add smoothly to the layer, instead they compete with the previous bass notes for the spot in the track it seems.
I watched Artiphon's youtube video again (last in the basics course) where "Petey" adds a second layer of lead onto his existing one. I can't do that.