Does the manufacturing process require more “activity” than originally anticipated?
If by, “originally” you mean when the FDA accepted the initial NEO IND in Mar 2017 (#msg-129238272), we know the answer to your question is yes. ADXS acknowledged one year later that it made “enhancements” to the production process and resubmitted the IND with amendments (#msg-139365653).
There are a great many things that can go wrong in the production of a personalized vaccine, so I don’t even want to speculate on what the specific issue(s) needing to be resolved might be.