Manage Access in Shared Drives

Problem

A user in a Shared Drive lost their ability to make changes to the Shared Drive, despite having a Manager access level.

Managing access levels of shared drives in the Admin console (as an Admin)

In the Admin console of your Google Workspace account.
Go to Apps > Google Workspace > Drive and Docs.
Go to the section Manage shared drives.
Find the desired shared drive, hover your mouse, and click on Manage members.
Find the affected user, and click on their access level, then select Remove Access.
Once removed, refresh the page, then locate the shared drive again, then click Manage Members.
To re-add the affected user, enter their email address on the small search box for Manage members, and select Manager for their access level, before sending the invite.

Go to Google Drive.
On the left hand panel, select Shared drives.
A list of shared drives that you are at least a member of will be available in this section; to be able to manage member access levels, you must be a manager for this specific shared drive.
On the concerned shared drive, click on the three dots and select Manage members.
Find the affected user, and click on their access level, then select Remove Access.
Once removed, refresh the page, then locate the shared drive again, then click Manage Members.
To re-add the affected user, enter their email address on the small search box for Manage members, and select Manager for their access level, before sending the invite.