Certain dependency sources are not loaded (although provided)

I've setup a basic Spring project and found that the sources from `spring-security-core-5.3.4.RELEASE` are not loaded in the editor.

The sources are downloaded and provided in the Project Structure configuration. Other dependency's sources are loaded as expected.

The sources are compiled with Java 8. Currently I have only IntelliJ's bundled Java 11 and macOS' Java 14 installed. But Java is still backwards compatible, right? ;)

Couldn't find another post with a solution. Any help is much appreciated!