Italic rendered as normal text in epub

[Kzer-Za]

See the screenshots. One of them is taken in Atril, a desktop application: the phrase "they have begun to arrive" is in italic. The other is taken on a smartphone, in FBReader: the same phrase in the very same file is rendered as normal text.

Since quotes are usually "highlighted" only by being rendered as italic, when they are not, it becomes difficult to make sense of a sentence with a quote. Again, see the second screenshot. With the quote displayed as normal text the sentence is a nonsense.

In the file this is the place:

<p class="calibre6">“Thank you!” said Bilbo with a gasp. It was not the correct thing to say, but <em class="calibre5">they have begun to arrive</em> had flustered him badly. He liked visitors, but he liked to know them before they arrived, and he preferred to ask them himself

Also in the CSS of this epub file calibre5 is font-style: italic.