Italics disappear when I change the font

Sometimes I get sick of staring at the same font over and over again. So I wanted to change the font of my novel. I couldn’t find a way to do this, apart from just selecting the whole manuscript and manually changing the font.
Not ideal, but it seemed to work.
It was a big mistake.
Today I realised that for some reason, when I changed the font, it erased all instances of italicized words/sentences.

So my question is, is there a way to change the main font of the whole project without deleting italics or bolds, or am I forced to look at the same font the rest of the time I’m working on my novel?

I’ve already tried making a seperate ‘body’ and ‘italics’ style, but the italics style would apply itself to the whole paragraph instead of just a word. Also, I tried to use ‘emphasis’, the character style, but that one also disappears the moment you change the font.

I hope someone can help me out. Thanks in advance!

Most likely one of the fonts you were looking at lacked italics. Unfortunately with the way the text engine works, if it can’t display bold, italic or any other variant (demibold, light, oblique, etc.) that had been applied before, then the formatting is dropped. It’s not ideal, but at the same time there isn’t a really good solution for how to handle that case anyway. What is technically happening here is that italics is font, and when you change the font family (which is a group of fonts responsible for displaying text in different weights, styles and combinations thereof) on a paragraph it looks for a regular Roman font for the body text and then it looks for an Italic font within that family for italicised text. If there is no such font, then it drops back to Roman. There is no “italic” in the sense of some kind of formatting command that exists above font declarations that could be retained despite the font family not having the font.

As for best practices: select all of the documents you want to convert, and use the Documents ▸ Convert ▸ Text to Default Formatting menu command—probably with the Convert font only setting enabled, but have a look at the other options.

As you noted, paragraph styles exert their stored formatting across the entire paragraph. There are consequently the worst tool for the job if you’re wanting to change the font family because they will by design obliterate most inline formatting by design, regardless of whether the font family has italics.

Thank you, @AmberV! It has nothing to do with the font lacking italics, though. I tested it and it also happens when you select a font that definitely has italics.

Okay, I’d need a checklist showing what steps you’re taking then, including the source and target fonts. I can say that generally this isn’t a problem, so it must be something specific that I’m not thinking to try.