I am working on a SuiteScript 2.0 client script.  I find that sometimes setCurrentSublistValue works, and sometimes it bizarrely claims that it is "not a function".

This question is pasted all over the internet, on stack exchange, and everywhere else.  No one has answered it.  I searched here and didn't even get one match.  Can someone provide some useful information ?  There seems to be something missing from my understanding of the api.