SonarLint plugin for IntelliJ Idea processes Kotlin source files just fine, but running ./gradlew sonar and using SonarSource/sonarcloud-github-action in Github Workflow doesn’t index any source files.
As far as I can see, your project is multiplatform, and we only started supporting Kotlin multiplatform recently. So you should use the latest sonar gradle plugin and apply it in your build configuration: Gradle - Plugin: org.sonarqube
Then you will need to run ./gradlew sonar after building your project to get the results. If this is not working, I encourage you to provide the logs and your configuration here.
I’ve migrated my pipeline to use the latest Sonar Gradle Plugin, as you suggested, and it’s working now, source code gets scanned.
Maybe it might be beneficial to leave a note at SonarSource/sonarcloud-github-action’s page on GH Marketplace mentioning Gradle is not fully supported at the moment.