Disclaimer: I have never tried this so there is no guarantee that it will work.
What about adding a Scripted Assertion into the Live Invocation Step?
Move the Assertion above the Learning Mode assertion so it executes prior.
Assertion psuedo-code:
if the live response's, meta data, http response code starts with "2" or "20" AND
if the lisa_vse_execution_mode = "LEARNING"
continue
else
branch to the Responder step.