default theme, clean install version 4.0.2.2
add some items to your basket then go to SHOPPING CART PAGE where you can REMOVE or change quantity and update...
if you PRESS REMOVE OR UPDATE on any product (whether changing quantity or not) then the COMPLETE CART is ERASED and you have to ADD ALL AGAIN
i rechecked on 4.0.2.1 and it doesnt do this, maybe we could replace the file controlling this with the file from 4.0.2.1

i tried some things but couldnt get it to work.
Note it only affects the actual PAGE index.php?route=checkout/cart&language=en-gb
It doesent affect the REMOVE button on the little popup box when you click on the mini cart button (top right black button)