What version of Sonarqube? If 6+, there are 2 plugins you will want/need installed.
SonarKotlin and Jacoco plugins.
The Jacoco plugin is relatively new. Read it’s docs as it requires specific output format.
If you follow instructions for both of those, and don’t see results, let me know. Had it working with old version, corporate Sonarqube was updated which broke coverage, and I discovered addition of Jacoco plugin, and config requirements.
Followed instructions, and it worked. Found using Docker to run a local Sonarqube VERY helpful.