Issue:
Customers are unable to add to cart without being logged in.
Version Control
YITH WooCommerce Wishlist Plugin v2.0.5 (Latest as of 2015-03-27)
WooCommerce v2.3.7 (Latest as of 2015-03-27)
Legenda v2.6.3 (Latest as of 2015-03-27)
Reproduce
Install a fresh cart and install above versions.
Use fresh browser session
Resolution
Downgrade YITH WooCommerce Wishlist Plugin to v2.0.1 via the EightTheme “Download Plugin” area:
https://www.8theme.com/download-plugins/