A filter named after one form will fire on another
Checkout rejected a name that was plainly filled in. The validation was correct, and it was running somewhere its author never intended.
Category: WooCommerce
The order saved, the payment worked, and checkout showed an error
A bot-protection widget on a multilingual checkout can fail at the very last step, after the order exists. The customer sees a crash and orders twice.
Your script runs too late to change what the app already read
Filtering data in the footer does nothing when a JavaScript application consumed it halfway up the page. The window you need is narrower than you think.
Why your shipping rates arrive attached to the wrong classes
Shipping classes are referenced by internal ID, and those IDs differ on every install. Copying the configuration between sites quietly scrambles it.