Study Library > Me > All terms - you can see every term you've ever studied/blocked on the site (split up by grammar/vocab/kanji), so you can get the full list there.
When trying to filter the blocked terms, it loads infinitely and prints the following error message in console:
VM62:1 Uncaught SyntaxError: Unexpected token < in JSON at position 0 at JSON.parse () at Function.n.parseJSON (main.20190110.js:4) at preProcessJSON (main.20190110.js:2810) at Object.postLoadList [as success] (main.20190110.js:1379) at i (main.20190110.js:2) at Object.fireWith [as resolveWith] (main.20190110.js:2) at z (main.20190110.js:4) at XMLHttpRequest. (main.20190110.js:4)