virtualbox.org

I have just installed VirtualBox 5.2.12.
I am hosting on MBP 2011 High Sierra 16GB Ram 1TB SSD
Installed Windows 10 (Home) and all was working just fine, I could access shared folders and both the trackpad and Bluetooth mouse were working just fine, in both environments (OSX and W10)
After about 4 hours of use, Windows installed several updates (rebooting in between), but now as soon as I start Windows 10, the Bluetooth mouse connection is lost in both environments, yet the trackpad continues to work.
As soon as I close Windows 10 and return to OS X the bluetooth mouse springs back to life
I have searched prior posts, but I have not found anything resembling my question.
Have I done something wrong?

Looks like setting VirtualBox to PS2 mouse, and disabling the Apple USB Bluetooth Host Controller, appears to have "fixed" the issue. Now just use the left Command key to switch windows.

It sounds like you've created a blank USB filter. Take a look under VM Settings » Ports » USB, and see if you have any filters enabled. Delete them.