Venom has 2 methods of routing MIDI data to and from its Arpeggiator.  This routing assignment is made in the MIDI section of the Global Page in the Vyzex Venom Editor Software.  Click the box to toggle, or right-click (Ctrl+Click on Mac) to select a mode from a pop-up menu:

“Local + Keyboard” sends arpeggiated notes to the Venom's sound engine while sending the notes as played on the keyboard out over MIDI.  The notes received from MIDI get arpeggiated.  In this configuration, pressing and holding a note will only record 1 MIDI note in your software.

“Local + MIDI” sends arpeggiated notes to the engine and out over MIDI.  Because each individual note that is arpeggiated is sent and recorded to your software the notes received from MIDI do not get arpeggiated.