Right - so while the symptoms are the same, the source of the symptoms doesn't appear to be the same as my case.
Did you try rebooting your computer? Maybe some ghost process holding a lock of some sort?
I have rebooted several times. Next steps I guess will be to swap out USB cable, even though the current one is working with the standalone FractalBot. If that doesn't help, I will reapply the 5.0 firmware update. Surprised no one else is reporting this issue. Lucky me.