I normally use vmware but when I have issues I create a brand new virtual machine, connect an ISO of BESR 8.5 and restore just like I'm restoring to physical hardware by mapping to a network share where the images are. The reason I use VMWare with BESR is that the converter is free and knows BESR images natively. I've had issues convertering using Symantec converter because it converts just the disk and doesn't create virtual machine startup file.
Try to restore using the ISO in a VM and let me know how it goes, I've done quite a bit of BESR installs (few hundred) maybe I can find a solution for you