The latest JIM version ships with the beta version of JSON importer/exporter. However, the JSON importer/exporter modules are not enabled by default, hence the modules needs to be enabled manually by going to Administration > Manage Add-ons > Show System Plugins > JIRA Importers Plugin, and enable the following modules:

• JSON (beta)(searchrequest-json)
• JSON (beta)(issue-json)

However, this step is not documented anywhere in the JIM documentation. It will be great if we can have this documented in JIM documentation, so that users will know that they have to enable the JSON module first before using it in JIRA.