Known issue in general with Fusion when guest operating systems are running when Macs are put to sleep. I just ran into this (again) yesterday on an Intel Mac when I walked away from a running Tumbleweed VM and the Mac went to sleep.
I don’t know if it’s coincidence or not, but I was able to get it back by suspending the VM, then resuming it. At that point the lock screen reappeared and I was able to log back in.
- Paul (Technogeezer)
Editor of the Unofficial Fusion Companion Guides