Windows has its own trusted root CA certificates (which is also used by Google Chrome browsers). If your company is running your own internal CA, an additional CA certificate has to be added to it.

I encountered a very strange problem where everytime I import it via certmgr.msc the dialog says The import was successful but the certificate was never imported.

Solution 1: Use Administrator Elevated Privilege

1. Click on windows icon -> Search for cmd
2. Right click cmd.exe -> Run as Administrator
3. From the command prompt, run certmgr.msc
4. Continue with the import process

Solution 2: Edit Group Policy on Domain Controller

It is common for PCs in office environment to be connected to a network domain. The default domain policy is to disallow users from adding their own trusted root CA certificate.

To get around this problem, use group policy management editor on your domain controller and find **Certificate Path Validation Settings**. Update the settings into following:

See this Microsoft article for more info.