Issue Summary

Performing a JQL search using "Target end" or "Target start" dates returns 0 or incorrect results. For example:  'project = "Project name" AND "Target end" is EMPTY' returns data with Target end having actual date not EMPTY. The same for NULL.

Another example JQL that will break: 'project = ABCD AND "Target End" >= '2020-01-01' AND "Target End" < '2020-03-01''

Steps to Reproduce

1. Create a project and some issues
2. Create a Jira Portfolio plan using the new project
3. Update some issues in the plan with a "Target end" or "Target start" date
4. Perform the JQL search 'project = "Project name " AND "Target end" is EMPTY' or 'project = Blah AND "Target start" >= '2020-01-01''
5. Note the results return as expected. 
6. Complete a Full reindex. 
7. Repeat the same JQL searches. 

Expected Results

Return only issues with Target end where it's empty or returns the issues that meet that the JQL parameters. Note: Before the reindex, expected results are found. After the reindex they are not. 

Actual Results

It returns all data for both empty Target end date and non-empty.

Workaround

A background index will temporary remediate the issue. No permanent solution has been found.