I believe I've reviewed every post and tried every option going back several years without success. We used to be able to do this (although even then was a bit of an adventure)
Bottom line: the dialog below looks like my best chance of success -- but where are the users?
Users are in the project, the project has other admins (besides the overall Jira admins).
For any devs at Atlassian -- what is the logic that populates my options here?
At a loss.

Using Server Jira v8.6.1