When translating Trifles (play) from English to Russian, Content translation is not able to divide it into translation units based on paragraphs, as reported in this comment. Hovering the the first paragraph to add it to the translation shows the whole document highlighted:
When clicking on the paragraph to add it, the "Automatic translation failed!" message is shown, as a fallback the whole source article is copied over to the translation.
Inspecting the source article, the only apparent particularity is the presence of About and Italic title templates:
{{About|the play|the dessert|Trifle}}
{{Italic title}}
'''''Trifles''''' is a [[one-act play]]...
Further investigation may be needed to confirm the cause.