Updated to 13-STABLE in VirtualBox; on shutdown stuck after uhub[01] being detached

[parv]

Hi there,

I had updated FreeBSD, in VirtualBox 5.22 on Windows with EFI, from
12-STABLE
to 13-STABLE; upgraded the ZFS pools & the EFI boot loader. Currently
testing with 13 GENERIC kernel.

Now on shutdown, "shutdown -p now" (in single user mode, after manually
unmounting
ZFS datasets via "zfs unmount -a"), the shutting down process gets stuck,
and
CPU use jumps to 80% (Intel i5 6300U, 3 CPUs given to VM, of Thinkpad
X260). Last
few lines are ...

...
All buffers synced.
Uptime: <however long>
uhub0: detached
uhub1: detached


In the end I chose "Power Off" from VirutalBox menu. "Reset" reboots the
machine.
None of these have any effect ...
  - Send the shutdown signal
  - ACPI Shutdown

Help please.


- parv