I have an issue "A" and this issue has a priority "Blocker":

However, a "Sprint Board" shows a priority of issue set to "Major".

Then, I reindexed Jira and "Sprint Board" start showing a correct priority set to "Blocker".
Is it possible to show actual priorities of issue without manually calling Jira re-indexing or other ways to show correct priorities of issues on the "Sprint Board"?