osgrow.com
or
www.osgrow.com
to
https://www.osgrow.com
but the address:
https://osgrow.com
does not redirect.
this is most likely the cause of the problem.
the cart is stored in a session, so if a customer starts browsing your site using the address:
https://osgrow.com
and then gets direxted to:
https://www.osgrow.com
it will be a new browsing session and cause the cart to be emtpy.
you can use an htaccess rule with mod rewrite to prevent this from happening:
http://www.jhuskisson.com/code-tidbits/force-www-in-your-url-using-htaccess