Translation:The director asked the students to tell what had happened.
I translated this "The director asked the students to say what had happened." and it was marked wrong. I reported this. DuoLingo suggested "The director asked the students say what had happened." and I think this is not as natural or common in English, although an alternative translation that I think feels more natural to me would be: "The director asked that the students say what had happened."
Unlike many "command/advise" verbs, ask requires an infinitive clause rather than a that-clause as a complement.
The director asked the students to say what had happened.
Hmm, that would be a level of strictness in use of English that I wouldn't hold anyone to. I also don't see anything on that page you link to, that says that "Ask that..." is not a valid construction. Even if I did find one source making that claim, though, I'd still disagree. I'm a native speaker and I think language is flexible, I don't like the idea of extremely strict enforcement. This isn't something as egregious as misuse of their / they're / there, or things like that, grammatically incorrect things that are confusing or abrasive to read because the words have a different meaning.
I did a quick google search and found these constructions are very common in English, and that they have been around for a long time, for example this 1868 source:
And the construction is used in the Common English Bible translation:
So, yeah, I disagree.