If you are trying to do held fixed patterns, try creating them in some synth software, and exporting as .Wav loops and importing as multipads. The audio loops won’t follow the chords…

But yes, you are coming across the primary difference between arpeggiators and arrangers. The arranger doesn’t look at the notes you play to drive the pattern. It derives or extrapolates a chord from the played notes, then the pattern associated with that chord is played. An arpeggiators doesn’t care what you play, it just plays it!

Different strokes..!

There are some arrangers now that have rudimentary arpeggiators as well as arranger chord recognition, but even the best of them are far behind a modern workstation’s arpeggiators functions.