It seems that the arpeggiator doesn’t retrig the envelopes on new different notes because it doesn’t make a gate gap between notes. The sequencer well puts a gate gap between notes.
Is it a bug ?
I can’t reproduce or I don’t understand your description.
Do you use “hold” with the arpeggiator? Or do you hold the keys with your fingers.
What is your clock source (internal/external-Trigger/external-MIDI)?