No violation of rules is reported during CSS analysis

I´m not seeing any violated CSS-rules in my reports, although it seems like css analysis is done and I know I have some issues in my css-files that should violate some rules.

I´m using SonarQube 7.6 Community Edition.

I´ve tried to create a new project in SonarQube on a developer branch with the same css-files, and everything is shown as expected in the generated report, but I´m still not seeing any violated css-rules on my master branch, although both css-files and css-quality profiles are identical on both projects.

My project is a multi-module project which has been running on SonarQube for a couple of years without beeing used actively. It has been analysing Java, Scala and XML files. I´ve recently added following lines to my client/pom.xml:

   <properties>
       <sonar.sources>src/main/webapp</sonar.sources> 
       <sonar.exclusions>src/main/webapp/css/vendor/**,
src/main/webapp/js/vendor/**,src/main/webapp/templates/templates.js</sonar.exclusions>
       <sonar.coverage.exclusions>src/main/webapp/**</sonar.coverage.exclusions>
   </properties>

After adding these lines SonarQube started reporting rules violation on JavaScript, HTML and CSS on developer branch (as expected), but on master only JavaScript and HTML rules violaiton is reported. I cannot find any violated CSS-rules on master, although it seems from the logs that css-files are being scanned without problems.

[INFO] Sensor SonarCSS Metrics [cssfamily]
[INFO] Sensor SonarCSS Metrics [cssfamily] (done) | time=70ms
[INFO] Sensor SonarCSS Rules [cssfamily]
[INFO] Sensor SonarCSS Rules [cssfamily] (done) | time=4241ms