Not sure if this is a bug or not.

1.  Add a product to the shopping cart.

2. Click on Review & Checkout.

3. Click on "Back to Community"

4. Shopping cart persists.

5. Click on Shopping cart.

6. Click on Checkout

7. Click on "Back to Community"  <-  Shopping cart is dropped. 

 

So from the Checkout page, if you decide you want to go check a message or whatever and hit back to the community, your cart is dropped. 

If that behavior is consistently reproducible on your site, I would recommend submitting a ticket so we can take a look.

Will do, I'll check it out again today and make sure. 

Thanks
JM