working in the sandbox, Magento 2, here is the breakdown of the steps required to purchase one item using Express Checkout (part of this issue resides with Magento 2, possibly with my theme - Porto):
1. select product and product option
2. add to cart, select qty (1)
3. click cart icon
4. click Go to Checkout
5. select payment method (PayPal Express)
6. click PayPal Checkout
7. Nothing happens - no guest checkout, must enter email address
8. PayPal login or account setup
9. select payment method again (for some reason, now multiples of item in cart)
10. update cart to reflect correct number of items desired (1)
11. go to cart to verify correct number of items
12. paypal checkout, again
13. login to paypal, again
14. select pay with PayPal (qty now 2)
15. return to store page, open cart to verify 1 item
16. return to checkout, now only 1 item in cart
17. checkout - order success page, order # (if logged in, no success page or order number given if not logged in)
18. continue shopping, back to store home page, cart icon still shows 1 item in cart
19. Select different product category, add 1 item. Cart icon shows 1 item in cart
20. click on cart icon, shows 1 item
21. go to checkout
22. shows review and payments, proper 1 item
23. checkout
24. amount due is 2X the 1 item shown in the cart
25. return to store page
26. cart icon shows 1 item
27. go to checkout
28. reviewed payments is now correct, shows correct item
29. checkout
30. select PayPal pay now
31. invoice # on success page, cart icon shows 1 item still in cart
32. click on "continue shopping", cart icon briefly shows zero items then reverts back to 1
33. opening cart icon shows previously purchased item still in cart
34. click on cart icon item "x" to clear item, receive "Attention: the quote item isn't found. Verify item and try again". Counter goes to zero
Cannot provide link because I'm working in the sandbox. But these steps have been replicated several times.
Also, cannot purchase as guest in PayPal express, must login with PayPal account. Different than activity in Magento 1.
