Currently, only the changes made to a JIRA issue are sent over to Aha! through the webhooks. We should have a way to force Aha! to synchronize all descriptions and fields from JIRA for an entire release.
Thank you for your idea. The status of this idea was out of date. Since this was requested, we have made major improvements to our development system integrations, including Jira.
Linked records can now be updated in bulk using the Update records button on the integration settings page in Settings > Product > Integrations.