Agile sidebar is not rendered after the removal of the option to display the old projects page

Summary

The removal of the option to display the old projects page is causing the sidebar to disappear on attempts to navigate to the Agile tabs of the new projects page ("Backlog" / "Active Sprints") for customers who had chosen to disable the new projects page.

Steps to Reproduce

1. Navigate to the "Backlog" / "Active Sprints" in the sidebar with a user account that had disabled the sidebar in the past.
2. Notice the project sidebar is gone.

Expected Results

The project sidebar stays on the left-hand side at all times

Actual Results

The project sidebar disappears.

Notes

This issue is affecting production customers that had decided to opt out from the sidebar, and that got the newest version of jira-projects bundled in JIRA 7.0.0-OD-02-247.

Workaround

Navigate to Reports in the Agile Board and navigate to the projects page again and the sidebar will show up again. This will have to be done again on further attempts to navigate to either the "Backlog"/"Active Sprints" tabs in the sidebar.

Contact Atlassian Cloud support for a fix for this problem.