what you describe is incorrect. This is how the envelope works:
the envelope will restart from 0, assuming the signal you feed into its gate input crosses a threshold (i.e. goes from 0 to max amplitude on the input scope).
you have to turn off LOOP, otherwise the envelope will simply loop. and you have to turn HOLD on or off, depending on the behaviour you want:
if HOLD is on, the envelope will wait for your gate signal to go low before it enters the release stage. If HOLD is off, then the envelope will not wait and will go into the release stage as soon as the time in the sustain stage has elapsed.
so if you want to retrigger your envelope and you don’t want the sustain behaviour, you set LOOP and HOLD to off, and you apply a gate signal to the gate input which goes from 0 to max amplitude (it should already trigger when the gate crosses 25% of max amplitude).