Peter Scholze and Brian Conrad give some comments regarding Shinichi Mochizuki's work on the abc conjecture in the comments section of this blog post by Frank Calegari. They specifically point out Corollary 3.12 of IUT3 as a source of difficulty:https://galoisrepresentations.wordpress.com/2017/12/17/the-abc-conjecture-has-still-not-been-proved/ …
The answer to that point is Remark 3.12.2 (ii) of newest version of IUT-III
