Appointment date/time not showing in cart after a few orders

When creating a new appointment product the date/time gets pulled through to the Marketpress cart when clicking add to cart. However, after a few appointments have been added to the cart (either consecutively or from different accounts) the date/time does not get pulled through. It just shows the appointment product name.

The workaround is to delete all SKU variations of the product that have been created. Then the date/time will show when adding new appointments to the cart. Obviously this is not a solution.

Is this is a bug with the Appointments+ and Marketpress integration or some other issue?