Thanks for sending the repro project. The x=random(4) node's Sequence field is blank, so it defaults to the Dialogue Manager's Default Sequence, which is Delay({{end}}).
For anyone as dense as I am, it is THIS highlighted node that needed None() in its Sequence field, the same node that had the script on it. Not the node beneath it as I have it in this screenshot. Thanks again, Tony.
Glad to help! Any node that should be processed and then immediately advanced past should have their Sequence field set to None() or Continue(). (Either is fine.)