What determines who appears in Tempo reviewer list in JIRA?

[Lacey McDonnell]

I have, for example, a user who is a member of a few groups and only two have actual Tempo teams and leads, can see more than just those two people in the time approver dropdown.

Why is that?

[Sigrún Arna Sigurðardóttir]

Hi Lacey,

Users that appear in the reviewer drop-down list are users that have the Approve Timesheet permission within the Team you are a member of. 

https://tempoplugin.jira.com/wiki/display/TEMPO/Approve+Timesheet+permission

I hope this helps.

Best regards,
Sigrún
Tempo