We defined a few custom single user picker fields in Jira (ex. Responsible QA). These fields have been associated with the project, issue types, screens, schemes, etc. and work perfectly fine when you add someone to a ticket. So if I open a ticket, I can see that Paul Smith is listed in the Responsible QA field.
The problem we face is when you go to search and select the custom user picker as a field, only a few users/groups are displayed in the list of options. Typing the name into the field's typeahead yields no matches.
If I select one of the users that does appear, the search works as expected. If I switch to JQL and search for Paul Smith in the Responsible QA field, the search works as expected.
I've checked user settings for people who appear as well as people who do not appear and can't find anything different. For instance, only one admin (me) appears in the list while another admin with the same permissions and groups does not appear.
We're using cloud and have ~400 users (about half are inactive).
Is this a user setting I'm missing or a bug?