This is a permissions issue. Ask the 365 Admin to elevate your permissions.
Site Settings > People and Groups > select group you are a member of > Settings > Group settings
Here, you can toggle two settings:
- Who can view the membership of the group? "Group Members" or "Everyone"
- Who can edit the membership of the group? "Group Owner" or "Group Members"
This will apply to the group itself, so please ensure that the other members of this group are intended to have the same level of permissions. If this is not the case, you may want to request to be moved from one group to another.
I hope this clarifies!
A question on your permissions EStein, you say you are a
Site Owner. I think this term is muddying the issue - a site owner would normally have the
Full Control permissions (meaning they can do more or less anything when administrating a site). I think you've been told you are the site owner in the sense of 'this site has been set up for you and you are kind of responsible for it' rather than being the Site Owner in a technical/permissions sense.
There are plenty of MS instructions on permissions - for example here.
Following up Sarah's explanation, please see the screen shot below (after all, a picture paints a thousand words):