Yes from what I understand the Estate claims the character is under copyright because 10 stories remained under copyright in the US (and nowhere else I believe).
But that isn’t how things work and they don’t seem too successful at arguing the point.
Their latest attempt was with the Enola Holmes movie that came out recently.
Even then they argued it in somewhat round about fashion. Basically claiming that since Springer’s novels and the film depict a Sherlock with emotions, that they’re using copyrighted material from still copyrighted stories. On basis of Holmes being slightly nicer there.
I don’t think they would have gotten anywhere but it looks like Netflix and Legendary probably just paid them to go away.
Otherwise there are ton of public domain Sherlock things out there, and Conan Doyle’s Estate doesn’t seem to really bother anymore. Probably because 8 of those 10 have since hit the public domain, and the rest are clear in two years.
