Guys, please try the steps below:
1. Open your Boot Camp virtual machine but do not start it.
2. Open 'Configuration Editor' ('Edit' -> 'Virtual Machine').
3. Select 'Hard Disk' tab.
4. In the 'hard disk' settings pane, click the 'Advanced' tab.
5. In the 'Cleanup Boot Camp Partition' area, click the 'Clear' button.
6. Try to create a new VM via 'File' -> 'New'.