The most common occurrence I've had with it was shopping thru the window the software opens. Opening a window to ccl in another browser never had it happen to me but almost every time I forgot and tried to buy thru the softwares window it did.
The other was people intentionally leaving the order PayPal Pending as a type of free layaway. Just check out, go to Paypal and then X out of the window at PayPal instead of paying. Then at a later time they could send the funding or pay an alternate way letting the items be manually deleted or order completed manually.
So the question becomes, which case was it with your customer? Did they go to pay thru the software causing the problem, did they go to pay and change their mind after the PayPal page opened causing the PayPal Pending or did they simply want free layaway until they had time to check everywhere else on the planet for better deals or wanting to keep it available in case they still wanted it when the paycheck/allowance comes in at a later date?
I have to say I'm getting to be very fond of managed payments so most of my sales no longer go thru PayPal at all. CCL never did make that an option aka blocking PayPal entirely and its nonrefundable fee's.
They tend to say insanity is doing the same thing over and over again and expecting a different result. Expecting ccl to suddenly change and fix stuff would seem to be insane at this point so you might consider some alternative venues like I did. CCL is now in
since it would be considered insane to keep complaining about the same problems and limitations over and over and over and over again. Did anything from the 2016 improvement list they requested ever get implemented? Coupon sale/discount codes, multiple sales tax options, ability to turn off PayPal entirely, minimum purchase to check out by $ or item qty, Maximum qty of same item purchase, etc, etc...... There are a couple long threads buried here somewhere with more details back when there used to be hope.
REDWOLVES...led by Sam Hoooowwwweeeellllllll", cheered on by the Wolves Den...