Hi Stan
To reproduce the problem:
Register with joomla default register
You log in
Fill in the rest of the details in OPC, address, name, city etc in the checkout process
And you confirm the order.
Result: The defails of the customer are saved but no customer number/ ID is created.
If you go to "VM my account" page and click save, the customer ID will be created.
So I think there is a little bug here since I believe OPC should create the customer ID once the order is proceed no?
This solved for us the mistery of why we have so many users without customer ID and the reason is cause they registered via OPC (Doesn't seem to cause any serious trouble though)
Regards
VM 3.0.10 joomla 3.4.4 OPC 2.0.296.090915