Changed this into a question by adding the tag "question:question"
I can't seem to answer my own question even after following the tags "question" and "question:question". EDIT: the top of the page still reads "subscribe to answer questions on this topic", but I found that I could post an answer from the page https://publiclab.org/tag/question:question
You can change any research note into a question post by adding the tag
question:subject, replacing "subject" with the tag the question relates to.
Then, anyone following that tag will be able to post an answer to the question.