When commenting on an answer to a question, the Jira issues macro does not link the issue to the answer. The jira issues macro is available when asking a question or supplying an answer, just not in comment on an answer. I have attached a screenshot of the behavior of where it can be added, and where the macro does not work as hoped.
Use case from the customer:
I think this is a valid use case … a question from the field comes in regarding a customer issue; someone confirms that it is a new product issue and give a quick answer which will be the “selected” answer. Then he/she does some more research and creates reproduction steps and files a JIRA issue and updates his/her answer with the JIRA issue number by adding a comment to his/her answer for reference.