Assuming the access control steps have all been followed, very often you can resolve these kinds of problems with the eLicenser simply by restarting your computer.
Most USB-eLicenser issues can be solved by installing the latest eLicenser Control Center, which also contains an USB-eLicenser driver.This error is usually due to Windows 10 major updates - it can also be due to moving the Soft-eLicenser file from another machine.
How do I repair the License Manager? (Do I just redownload it from scratch? Do I need to make a note of all the license numbers first?)
Subsequently, can I delete the soft eLicenser inside the License Manager?
(Fortunately, Dorico will run from the USB elicenser. I just want to eliminate the error messages and be sure my license manager is okay for the future.)
EDIT: Just found out that the key was to run License Manager as Administrator. (I should have remembered that straight off.) So my difficulty has been solved.