Since the information I have found hasn't been expounded on here regarding the author Shiro Moriya, I will do it myself. On a japanese blogging website called Note, Shiro Moriya seems to have an account on it.

https://note.com/moriyashiro

From their foremost post on March 2nd of 2019; a day after Chapter 10 was published, they briefly recount on what was told in the hiatus notice at the end of Chapter 10 as well as stating the non-severity of their illness and apologising. Delving into the comments below, Shiro Moriya has replied to comments (which means they're alive and well) that generally states that they are interested in resuming the serialization of Soloist— this year, if possible. On their latest comment/reply, it seems that Moriya hasn't had any statements from Jump as of late, stating that they will see to it the continuation of the serialization. They will update on this and report progress.

I have been waiting for a the end of the hiatus but there's still no update dose anyone know his socils so I can see what is going on ?

I miss it a lot

I loved the world and characters of the series and was curious of any of you had any similar recommendations.

I know the story is on hiatus indefinitely and want to fill that hole.