Yes, the block list is empty, but the “warning list” is not. [1] The warning list is sadly not available through the public API.
The intended behavior for meanings on the warning list is for the input box to shake and show a message that they want a different meaning. A bug causes the answer to instead be marked wrong if the user has added this meaning to their user synonyms.
Can be checked with
(await fetch("https://www.wanikani.com/extra_study/items?ids=180").then(r => r.json()))[0]↩︎