Queries using dateCompare can return no issues, even when they ought to.
For example, the following query of the ScriptRunner for Jira project:
Looking at the browser's Network tools, you can see that there's an HTTP 400 error being returned by <jira base URL>/secure/QueryComponent!Jql.jspa .
While the error message itself seems to be a red herring (see JRASERVER-63507), we should investigate whether there are changes we could make to dateCompare itself to prevent this problem from showing up in the first place.
Some customers have been able to work around this problem by adding a subquery to their call to dateCompare. That said, the subquery, even a fairly specific one, will not always rectify the issue.