Automated Release Notes add-on uses power of JQL to automatically generate release notes from Jira. JQLs, if not used properly can end up retrieving data for thousands of Jira issues. For example, queries such as following could end in a large data set in search results.
Project = 'ARN'
Priority = 'High'
and so on
Such queries, if used within the ARN's JQL section, could be disastrous. It might mean that the add-on will try to retrieve 1000s of Jira issues & their required attributes. This can potentially slow down the host Jira instance & might as well bring it down if the search result set is huge.
To avoid this problem, by default ARN applies a ceiling of 250 issues on every JQL. That is, every JQL section will only fetch maximum of 250 Jira issues. But this can be a problem in genuine cases where higher number of Jira issues are required in release notes creation process.
Just navigate to 'Automated Release Notes configurations' as a Jira administrator & click on the 'App Settings' tab. Modify the Max Results setting, if required.