https://support.atlassian.com/browse/CSP-684 refers.

summary: exporting data from 2.0, importing to 2.3 meant some content wasn't available, traced to use of 'jira' shortcut. The 'expanded' value turned out to be missing, it had to be removed and re-added, which then allowed the content to be 'found'.

Reindexing was suggested but was not the problem. It was suggest I raise a bug here.