Overall Test Results gadget is not exportable from Jira's "Dashboard charts" tool

Description
Overall Test Results gadget is not exportable from Jira's "Dashboard charts" tool

How to reproduce

1. Head to Jira's Issue Navigator page
2. Go to "Export" >> "Dashboard charts"
   
3. Select the "Overall Test Results"
   

Actual result/Attachments
There is an error, and the gadget cannot be saved:

Expected result
The gadget is presented and can be saved to Dashboard