I am having this issue after I installed 18.104.22.168.
1/3 of my orders have wrong amount paypal. if no coupon applied, it always add  to the grand total. I have also noticed that the custom filed passed to paypal is empty on these problematic payments.
I am attaching 3 screen shots, you can see what I am talking about. So, is there a fix?
Click thumbnail to see full-size image