quanta magazine 2018.9.20でも　

Kim heard similar concerns about
Corollary 3.12 from another
mathematician,
Teruhisa Koshikawa, currently at Kyoto
University.
And Stix, too, got perplexed in the same
spot.
Gradually, various number theorists
became aware that this corollary was a
sticking point,
but it wasn’t clear whether the argument
had a hole or Mochizuki simply needed
to explain his reasoning better.