A. 1. Ensure you are logged into your account while shopping, as items may be saved to your account rather than the app's temporary cart. 2. Check if there are any session timeouts; try to complete your purchase in a timely manner.

B. 1. If items are still disappearing, consider taking a screenshot of your cart before checking out as a backup. 2. Try adding items to your cart one at a time and checking out immediately.