2-nosyl gives "Unable to assign all locants. This locant was not assigned: 2"
I think 2-nosyl is a thing. Sometimes also called o-nosyl. Clearly OPSIN doesn't want to hear about a locant and just defaults to 4-nosyl. FWIW, the Wikipedia page (which I did not edit :-) at https://en.wikipedia.org/wiki/Sulfonyl has both 2- or 4- listed as synonyms of Ns.