Looks like a possible security/permissions error. It might have not installed correctly due to an inability to create temporary or other directories due to a lack of security permissions. That has been my recent experience.
The problem you are having is becoming more common on certain Windows 10 Home tablets that are originally Windows 10 Home (never upgraded from 7 or 8.1), and originally installed with a more recent version of Windows 10 Home that has had their boot and other security continually "improved". I have never experienced this problem on any of my desktops. Remember that every Windows PC has a unique software environment. Other people do not have your exact hardware and software configuration and installation history.
I have experienced the identical problem on a 2-in-1 tablet and resolved it by upgrading from Version 1803 to 1809, which often repairs any security/permissions errors since it resets so many things in the upgrade process.
https://www.microsoft.com/en-in/soft...load/windows10
Regardless of the version, ensure you are an Administrator and not just a simple User.
If you were a simple User, after changing yourself to be an Administrator, reinstall/repair Calibre via its .msi file. It might have not installed correctly due to an inability to create temporary or other directories due to a lack of security permissions.
Run Calibre from a desktop shortcut for which you have changed the shortcut's Properties to always run as an Administrator.
I also found that installing the Calibre .msi by copying its path into a Windows Command Prompt Box with elevated (administrator) privileges works, even if one is already an Administrator. Right-click the Start button to find that option.
Good luck.
DaltonST