Hi @kelly.downs,
Not an error. And you’re not the only one perplexed by that 
.
There’s some discussions about that here (2018 Explore PT Written Response 2b or NOT 2b?) and here (Explore PT - Written response 2b, development process for creating artifact)
In short, officially (according to College Board), don’t skip it. Follow the written prompts even though it is not directly assessed in the rubric. Some say it may help address possible concerns of plagiarism.
Official CB response: “Students are required to answer all prompts.” (Source: CB Crystal Furman)(https://apcommunity.collegeboard.org/group/apcsp/discussion-boards/-/message_boards/view_message/129309386)
Longer answer: https://apcommunity.collegeboard.org/group/apcsp/discussion-boards/-/message_boards/view_message/130052688
(You need to have done the audit and login to your College Board account to view those discussion board posts)
Frank