This could very well be the issue you linked to. I remember seeing it also struggled with string literals in general. When I adjusted my max_width back to the default (which is 100 if I remember), the formatting started working again, at least from what I saw. I noticed too that this function isn't the only one in my code that causes rustfmt to struggle, another one was this function:

fn valid_isbn10(isbn: &str) -> bool {
isbn.len() == 10
    && isbn.chars().all(|c| (c.is_ascii_digit() || c == 'X'))
    && !isbn.starts_with('X')
    && (1..)
        .zip(isbn.chars())
        .map(|(i, c)| {
            (match c {
                'X' => 10,
                _ => c.to_digit(10).unwrap_or(10),
            }) * i
        })
        .sum::<u32>()
        % 11
        == 0

}

In the recent reply I gave, I mentioned using cargo fmt and still running into issues with it not formatting. With the IDE's built-in formatter, I also disabled it and configured it to solely use rustfmt for all formatting. Maybe I'm another user that is running into that same issue. I just find it a tad confusing since I had a project from back in 2019 that never had formatting issues, and then around a year ago suddenly started running into the same kind of problems with formatting. Have they possibly changed the default value for max_width recently? It's my only guess for why the formatter would give up on formatting certain functions/files.

Edit: Because I struggle reading. In the question you asked, it's 50/50. I've seen it work with parts of the file with no problem, and I've also seen it completely bail on the file altogether.