If I typeset

{\rm foo{\it bar}}

bar is not in italic

if I typeset

{\it bar}

it is.

What am I missing?

Gerben Wierda (LinkedIn <https://www.linkedin.com/in/gerbenwierda>, Mastodon <https://newsie.social/@gctwnl>)
R&A IT Strategy <https://ea.rna.nl/> (main site)
Book: Chess and the Art of Enterprise Architecture <https://ea.rna.nl/the-book/>
Book: Mastering ArchiMate <https://ea.rna.nl/the-book-edition-iii/>