OK, I have identified the problem. In VM Invoice, when creating a manual order, there are 2 different vendors listed, both with the same name as I only have one vendor set up which is myself. In Virtuemart, I only show one vendor. When I create a new order/invoice in VM Invoice, if I click on the vendor drop down, I see 2 instances of the same vendor name. If I choose the first one, it works fine and the order shows up in VM. If the second one is chosen, then it will not show up in VM. Taking a look at JOS_VM_Orders, the ones that don't show up use a vendor_ID of 2 while the ones that work show a vendor_ID of 1. Not sure where that other vendor instance is coming from.
Regardless, I still get the blank screen with a hang when I try to save the order. I had that problem with 1.6 and I believe you had me add some additional code that fixed this. I assumed this code was in the new version but will have to go check it out.
Any ideas where the second vendor is coming form and how to delete it so that it does not get accidentally selected in the future?