Non-project specific settings in Android Studio won't stick

A strange question but I'm baffled. I'm a long-time user of Android Studio and I never had this before. I have several projects set up and one of them (Android/Kotlin) always has its code settings set to Project instead of IDE. I would prefer the second, my usual code style preferences are stable across projects.

Whenever I open up this project (either starting AS fresh or changing projects), and I go into File > Settings > Editor > Code Style, it stays on Scheme: Project. If I change back manually, everything is OK until the next start, then it will be set to Project again. And as I mentioned, this is a single project that does it, all the others remember my preferences.

What obvious stupid little setting did escape my attention? AS 3.4.2, fresh. I don't use EditorConfig. Settings for new projects are IDE, too.