Cart is showing empty even after selecting products ??? Probably your cookies are disabled.
How to Enable it?
Please enable cookies inside your browser Privacy & security settings (Desktop) or Site settings (Mobile) as below.
Desktop Chrome: -> Settings-> Privacy & Security-> Cookies and other site data -> Select Block third-party cookies in incognito
Desktop Mozilla: -> options -> Privacy & Security -> Custom -> Check box Enable for Cookies.
Desktop Opera: ->Settings-> Privacy & Security-> Cookies and other site data -> Allow All cookies / Block third party cookies