Aggregate functions do not always display calculation

The problem

The JQL function aggregateExpression does not displays the result when you click Search (it only does when you click Enter)
The main problem comes when you save the JQL in a filter, and then you select that Filter - nothing is displayed (unless you hit Enter)

Steps to reproduce

• Log some time in an issue (lets say 8h)
• Run the following JQL

  issueFunction in aggregateExpression("Time Spent SUM", "timespent.sum()")
  

• Click Search (the expected result is to see the relevant message - but nothing appears)
• Now Click Enter (the result appears as expected)