it sounds as if the vca is not closing properly - nb I don't have any of these modules
try taking the vca out of the patch - try gate from keystep straight into the vca cv input... does that behave as expected - ie when you press a key the note starts and when you release it the note ends? remember a gate is a type of envelope that just goes fully on, sustains (whilst the key is pressed, in your case) and then off again
if this is working what happens when you ignore step 4 above and then manually trigger the envelope with the button on ceis?
Utility modules are the inexpensive, dull polish that makes the expensive, shiny modules actually shine!!!