Missing filter in "Helper"?
After selecting a project in the details section of the Customize Panel Configuration Page the "Helper" will provide a list of predefined/saved filters. Selecting a filter will paste the JQL from the predefined filter to the "Filter" field.
The list of filters displayed in the "Helper" includes:
Filters shared with the selected project.
Filters shared with the current user.
Please check if the expected field is shared with you or selected project.