Summary
The dashboard gadget "Average Time in Status" only pertains to issues that are already resolved.
The gadget does not cater to issues that are not yet resolved.

Request to create a gadget that shows average in time in a specific status for non-resolved issues.

How to Replicate

• Login to cloud instance
• Access Jira product > Dashboard > Add the gadget "Average Time in Status"
• Configure the gadget with the appropriate status (in this case, Selected for Development)
• Click the graph create, and you will see the JQL is always in this status/time format:
  “project = xxxx AND resolved >= 2021-11-04 AND resolved <= "2021-11-04 23:59"

With the above example, if you have the following:
3 resolved/done issues
3 issues still under “Selected for Development” workflow

See pic 1 for reference.

The gadget will only show 3 issues, it only shows issues that went through 'Selected for Development' workflow but now are resolved. It does not count the issues that went through 'Selected for Development' status but are not yet resolved.
See pic 2 for reference.
See pic 3 for reference.