JetBrains Mono and merged title bar only on first start

I’m experiencing some very strange behavior. I updated from IntelliJ Idea 2019.2.4 to 2019.3.1 to get access to JetBrains Mono. So I first launched the new version and chose to import the old config. I was pleasantly surprised that I also got the dark merged title and top tool bar. I changed my editor font to JetBrains Mono. Then I restarted IntelliJ to apply changes to plugins. I then didn’t have the merged title and tool bar and JetBrains Mono want in the font list anymore. I tried rebooting, didn’t fix it. Also deleted the config folder and imported from 2019.2.4 again, got the same behavior.