PayPal Advanced Checkout order sometimes "not finished"

PayPal Advanced Checkout order sometimes "not finished"

Sometimes Orders with the PayPal Advanced Checkout does not finished, (not paided) although these were credited in our PayPal Account. I remember we had this problem before with the old PayPal version, and they fixed it. What could be the problem?

I just wanted to enable the log file for the payment process. However, I can't select this option....

JS 5.5.5

Do you have any idea what the problem with PayPal could be? Out of 50 orders, it may apply to 1.

Aw: PayPal Advanced Checkout order sometimes "not finished"

Would it help to select "paid" here? I don't understand the function behind it. What exactly happens if a customer doesn't complete the payment process? Would the order still be marked as paid?

Aw: PayPal Advanced Checkout order sometimes "not finished"

log?

configuration / General
Save info to Logfile
Save info Payment to Logfile

Aw: PayPal Advanced Checkout order sometimes "not finished"

OK, I've activated the Log-feature and will send you the file if this happens again.