Virtuemart cart page is not cached

i am testing a LiteSpeed cache plugin in Joomla with Virtuemart and i have noticed, that all pages are cached (in header i see x-litespeed-cache: hit). Only cart page is not and x-litespeed-cache: XY is missing. Is that purpose or not? and how could i define this behavior?

You can check it here: x-litespeed-cache is not in header x-litespeed-cache: hit is in header