I had the same problem after Update.
What i did was set Chipset/Firmware Type to: " I440FX Chipset with BIOS " and
it works.
Previous setting was "Q35 Chipset with BIOS " , which did not work with 4.4.3 .
I also can not change the Cluster Compatibility to 4.5 and if i want to do Spike VNC in
any vm`s using Remote Viewer via Console Tab in Gui , it does not open any connections.
Maybe i need to change the Cluster Compatibility for this to work, but i dont know how
that works.