Cannot add items to Guest account

1 week ago
We are in the process of upgrading from 4.1 to 4.3. In our deployed 4.1 site guests can add multiple items to their cart.

In our local environment using 4.3 code guest cart only ever shows 1 item. In the nop DB it looks like a multitude of guest accounts each with 1 item (shopping cart item table). We are aware of the issue with guest accounts being created. However, it might be the case now that each time 'Add to Cart' is selected, the product is put in shopping cart of a new guest account, and so there is only ever 1 item for a guest account.

This is just a guess based on what we see in the nop DB. The issue might be something else.

Is this a known issue? Any advice on how to fix this? Registered users can add multiple items without issue.
1 week ago
How are you running your "local environment" - IIS?  (You may need a machine key)