VirtualBox on Windows 10 64bit doesn't have a 64bit option [duplicate]

I've read previous threads about this issue, but none seemed to help.

I'm running a 64bit version of Windows 10 on a HP Elitebook. I've installed VirtualBox and wanted to create a 64bit Linux VM. However, I can only select 32bit OS'es in VirtualBox.

In the BIOS, I've got both VT-x and VT-d enable, and I've disabled HyperV in Windows, but I still don't have the option to select a 64bit OS.

What am I doing wrong?

Solution 1:

Turn off Core Isolation in Windows Defender

If duDE's solution didn't work, check Windows Defender > Device Security > Core Isolation Details and make sure this setting is turned off.

Core isolation [includes] security features available on your device that use virtualization-based security

Which is why Core Isolation interferes with VirtualBox.