Hey Jira Community,
we have a Jira project and the Sidebar is only visible for the owner´s of the Jira Project.
Every other project members cannot see the sidebar (see screenshot). Assignment for the users who cannot see the sidebar is Developer and Administrator.
I think this is an authorization problem. The browser inspection console shows a lot of 403 errors.
We tried to resolve this problem by assigning the "Administrator" role by the affecting users, by disabling adblocker extensions, by disabling any VPN connection, by deleting browser cache & Cookies, all of that without success.

Affected Jira Version: Atlassian Jira Project Management Software (v9.12.8#9120008-sha1:2523b75) (free community license)
This Jira instance is hosted in our data center