Q: When I press the "stop" button on the Keystep37, to stop the Keystep sequencer/arpeggio, the Argon8 Amp envelope inverts and stays inverted, meaning that there is no sound.
What is most likely happening is your Arturia product is actually transmitting data when the transport controls are used.
If you have Arturia's MIDI Control App then we believe the solution to your issue is either to change transport controls or to filter out incoming CCs on your Argon8 either using the front panel options (as discussed on page 54 of the Argon8 Owner's manual) or the MODALapp.
You can download the free MODALapp here.