Hi, Mary.
Since your computer is new and/or as a result of the version upgrade, it is possible that this issue is being caused by a feature in Windows 10 called "fast startup". Information and instructions on how to check and disable fast startup at the following links:
https://www.windowscentral.com/how-disable-windows-10-fast-startup or
https://www.tenforums.com/tutorials/4189-turn-off-fast-startup-windows-10-a.html . If fast startup is enabled, try disabling it and restart the computer. Then check to see if Ransomware Protection functions as it should.
If fast startup is not enabled or disabling it didn't solve the problem, you'll need to do a clean install of Malwarebytes by following the instructions below:
Note: If you use the tool to do a clean re-install, it will preserve your key. However, before you proceed with the following, I suggest that with Malwarebytes open, you click on the Account Details tab and carefully write down your license information.
1. Download and run the Malwarebytes Support Tool from
https://downloads.malwarebytes.com/file/mbst2. Accept the EULA and click
Advanced tab on the left (
not Start Repair)
3. Click the
Clean button, and allow it to restart your system and then reinstall Malwarebytes, either by allowing the tool to do so when it offers to on restart, or by downloading and installing the latest version from
https://www.malwarebytes.com/mwb-download/thankyou/.
As to scanning for rootkits, just doing a regularly scheduled scan is sufficient.