VirtualBox Core Isolation (also called Windows Hypervisor-enforced Code Integrity (HVCI)) issues should be fixed in VirtualBox version 6.1.32 (and above). Quote VirtualBox changelog
:
VMM: Changed the guest RAM management when using Hyper-V to be more compatible with HVCI (bug #20627
Could you please confirm that Windows Core Isolation is no longer an issue?
This also got finally a dedicated documentation chapter:
https://www.kicksecure.com/wiki/VirtualBox/Troubleshooting#Core_Isolation