We have two different internal tasks, one is called Adhoc Meetings and the other is called Adhoc Requests, however when a user is attempting to add a timesheet in the Calendar view and is using the search bar, if they type Adhoc it only shows the Adhoc Meetings task, they have to manually Type the Task Id to be able to select the task.
We would like for the search filter to work as intended so they don't have to remember the task Id for tasks not showing up from the filter
From the support team, it appears the limitation is:
"primarily due to the search field relying on a single Jira API call, which is not always returning the expected results" with the api being rest/api/3/issue/picker