This is something that needs to be fixed.  Because my invoice showed "viewed", I was under the impression that our invoice was on scheduled to be paid.  Come to find out when I checked with the customer on the due date (60 days later), they never opened it to enter it in their system.   Now I have to wait an additional 60 for them to enter it and then release payment.  If it hadn't been marked viewed, I would have seen that and could have contacted our customer sooner.  Are there any plans to update this feature so that you can see exactly who views the invoice?