When I add items to my cart the grand total updates correctly but when I visit /checkout/cart/ for the first time the grand total is zero although the items are listed correctly.
Refreshing the cart page corrects the total, so this only happens on the first view. Subsequent visits to the cart page are correct so I'm guessing it's something to do with the session but don't know where to start.
Any help appreciated.
Best Answer
That might be related to an extension that hooks into the collectTotals() methods, which are called on every refresh of the cart. If an extension relies on data that is not present yet at the first time the totals are collected, it might mess them up.
To debug, search for
_collect_totals_and_collect_totals_in all config.xml files belowapp/codeand see in which modules you get results (excluding those from core/Mage). You'll find observer definitions for events likesales_quote_address_collect_totals_before.Disable all extensions you find, and if this solves the problem, enable them again one by one until it appears again. Then it's time to examine the observer code and/or contact the extension vendor.