Same here. It seems to occur if I use import Playgrounds and the #Playground macro in a SPM module. So far I haven't found a workaround. Just don't use the playground macro. (Side note: Why do I feel that it happens all the time that features are made for WWDC presentations, but do not work at all in reality, and fail in the most basic setups? I came to the platform, because it didn't use to be that way…)

I realized that if I delete all code except for one Preview, it still does not work. If I then remove all SPM dependencies, the Preview works. It doesn't work if there's even one dependency, no matter which one. Hope that helps in finding the issue.

Filed feedback with diagnostic information as FB14728865

Got the same issue in Xcode 16 Seed 5 (16A5221g)

In the CarPlay video they talk about SF being a variable font, that can adjust boldness, italics, roundedness etc with arbritary values. I did not research how deep you have to go down in the font system, but that seems to be the way to do this. Those glyphs are not a special font, but a different set of those variable parameters.

Got the same. Everything seems to work fine though, but the warning has been there for a few betas already…