JQL search is not working properly when used with participant custom field

Question

Issue with Re-Indexing.

The below query throws around 40 issues after completion of Full Jira Indexing, and after Project Re-indexing it gives the actual result of around 14000 issues.
If we do the Jira Re-Indexing again the issue counts reduces to 40.
project = TSR AND issuetype = TSR AND Participants = qc02694 ORDER BY key DESC

Participant field from Plugin "Jira Toolkit"

Daniel Ebers · Answer

Jira Toolkit App, unfortunately, is "unsupported". There will be most likely no support be available for it.

Is there probably anything suspicious visible from atlassian-jira.log - that, indeed, might not be the case but it is a try to catch an error message there if the situation should be logged.

Alexander Pappert · Answer

then you should open a bug report at the vendor at marketplace, when it is from a plugin CF