While this workaround (run Toolbox as Admin) "works", it really does not work: On a properly configured system (one on which the normally logged-in user is NOT a member of the Administrators group), this will result in Toolbox saving scans into the local folders of the (other, administrative) user as which Toolbox runs after the (non-Admin user who needs to scan something) responds to the Windows UAC prompt with an admin user ID and password.
Additionally, it's never correct to tell a user "that normal user function requires administrative privileges to work".
That Toolbox cannot find the (installed, works with Windows Scan & Fax) scanner, means that something about the way the Canon drivers install the device set the device permissions incorrectly, or, more likely, that something about the way the ancient MF Toolbox software was (mis)written is trying to do something wrong.
Despite the fact that this is older software, it goes along with hardware that is meant to last for many years (my MF6550 is 14 years old and still works fine), and Canon morally owes it to the user community to put a bit of software re-engineering effort in to updating MF Toolbox to make it work on modern Windows systems.
