Jira does not reindex issues after a link is added to them

Problem Experienced

When a link is added from the issue (e.g. by selecting More->Link on the issue view), both the database and Lucene index are updated.

When a link is added to the issue (e.g. by mentioning it on a Confluence page or creating a reciprocal link from another issue), the database entry gets updated, but the Lucene index does not.

Expected Behavior

The Lucene index should get updated in both scenarios.

Notes

As far as I can tell, this is not a problem from the end-user perspective (they are still able to see proper content in the "Issue Links" panel, and there is a proper entry in the "History" tab).

The issue, however, makes index consistency analyzer tools unreliable, because they contain many entries with different "lastUpdated" times in the index and in the database, making them hard to use due to a lot of noise.