Sometimes an uninstall/reinstall can fix issues with the add-on - please use the steps below:
In Google Docs, click Extensions Add-ons Manage Add-ons:
Find the Lean Library Workspace add-on, click the 3 vertical dots icon and select Uninstall:
Then reinstall using the link below:
https://workspace.google.com/u/0/marketplace/app/Workspace/800143025315