Hope someone can help me with my problem. I've already fixed this before by checking the 'Clear Cart When Logging Out' option in the Woocommerce Settings. But for some reasons I don't know, the problem came out again lately. When User 1 logs in and adds items to his/her cart and logs out without checking out, then User 2, 3, or 4... logs in. what they see in their cart are the items of User 1.
What could possibly be the problem? Hope to hear from you soon. Thank you.