After contacting Paypal several times a possible solution for the Safari empty cart syndrome has been found.
I have done some preliminary tests on both an Mac and iPad and so far it works.
Paypal stores the cart contents in a browser Cookie, Safari is set at default to reject
cookies from pages you did not directly visit, since the item is sent from the shopping
page it means that you did not directly visit Paypal and so it does not store the Cookie containing the cart contents.
The cure is simple
On a Mac, go to Safari menu / Preferences, then select the "Privacy" tab in the window that opens
now under "Block Cookies" click on "Never". That's it . It should now remember your cart content.
For iDevices (iPhone, iPad...). Open Settings then click on Safari in the left column.
Now under Privacy tap on Accept Cookies and tap on "Always". Close settings and you are done.
It has come to our attention that the Safari web browser is not 100% compatible with Paypal, our payment system
If you use safari, items placed in the shopping cart may vanish while adding new items.
It's very erratic and may work sometimes but is a major issue when adding a large number of items.
The more items you add to the cart the more likely you are to experience loss of items already in your cart.
To solve this problem you have 2 choices, use a different web browser (see links below for Mac compatible browsers) or email
A list of all the items you wish to purchase to me using the email link on the CONTACT page.
It's better if you use a different browser, and as you can see by the list below, there are plenty of free Mac browsers available.
If you have any questions, please don't hesitate to ask