I installed a bunch of Myriad Pro variants in Font Book and was using LuaLateX to set the section headers to this font:
\newfontfamily{\headingfont}{Myriad Pro}
\renewcommand{\maketitlehooka}{\LARGE\headingfont}
\titleformat{\chapter}[display]
{\headingfont\huge\bfseries}{\chaptertitlename\ \thechapter}{0pt}{\Huge}
\titlespacing*{\chapter}
{0pt}{0pt}{30pt}
\titleformat*{\section}{\normalfont\LARGE\headingfont}
\titleformat*{\subsection}{\itshape\Large\headingfont}
\titleformat*{\subsubsection}{\normalsize\headingfont}
However I noticed it was using the condensed italic for the italic font.
I then noticed I didn't have the regular italic font installed. So I installed it, but no change.
Removing the condensed italic I then got an error that the italic font could not be found. What is going on?
This is the output of fc-list (when the condensed fonts were installed)
./fc-list | grep "Myriad"
/Users/xx/Library/Fonts/MYRIADPRO-SEMIBOLD.OTF: Myriad Pro,Myriad Pro Light:style=Semibold,Bold
/Users/xx/Library/Fonts/MYRIADPRO-REGULAR.OTF: Myriad Pro:style=Regular
/Users/xx/Library/Fonts/MYRIADPRO-COND.OTF: Myriad Pro,Myriad Pro Cond:style=Condensed,Regular
/Users/xx/Library/Fonts/MYRIADPRO-BOLDCONDIT.OTF: Myriad Pro,Myriad Pro Cond:style=Bold Condensed Italic,Bold Italic
/Users/xx/Library/Fonts/MYRIADPRO-BOLD.OTF: Myriad Pro:style=Bold
/Users/xx/Library/Fonts/MYRIADPRO-SEMIBOLDIT.OTF: Myriad Pro,Myriad Pro Light:style=Semibold Italic,Bold Italic
/Users/xx/Library/Fonts/MYRIADPRO-CONDIT.OTF: Myriad Pro,Myriad Pro Cond:style=Condensed Italic,Italic
/Users/xx/Library/Fonts/MYRIADPRO-BOLDIT.OTF: Myriad Pro:style=Bold Italic
/Users/xx/Library/Fonts/MYRIADPRO-BOLDCOND.OTF: Myriad Pro,Myriad Pro Cond:style=Bold Condensed,Bold
/Users/xx/Library/Fonts/MYRIADPRO-IT.otf: Myriad Pro:style=Italic
lualatex
to update its information about fonts, especially if you are using an older version of Mac TeX but possibly (I'm not sure) even if you are using the current one. Or you might need to specify the italic explicitly... (less likely for this font, I think).