Whonix 11 Gateway and Workstation (latest release) won’t be able to bootstrap TOR unless I switch Network Adapter from NAT to Bridge - then it will work just fine - under Windows 10. Debian Linux works fine when using Whonix 11 via VirtualBox.
OP - solution to this problem? Bridge can cause known security issue unless it’s switched back to NAT otherwise Bridge will broadcast my network location to the rest of the node which I want to avoid.
EDIT: nevermind, apparently only one program can request TAP driver at a time. Disconnect.me (desktop edition) was using TAP driver so VirtualBox wasn’t able to request it because it was in use. Make sense now, now it’s working just fine. Lesson learned. All I had to do is turn off Disconnect.me - that’s it.