Unfortunately, it’s not as trivial as excluding individual files.
Can you check that the scanner is definitely recognising the SONAR_SCANNER_OPTS environment variable? You should see something like this at the begeinning of thee scanner logs.
INFO: Scanner configuration file: /Users/colin/Tools/sonar-scanner-4.0.0.1744/conf/sonar-scanner.properties
INFO: Project root configuration file: NONE
INFO: SonarQube Scanner 4.0.0.1744
INFO: Java 11.0.3 Oracle Corporation (64-bit)
INFO: Mac OS X 10.15.4 x86_64
INFO: SONAR_SCANNER_OPTS=-Xmx2048M -Xms2048M
INFO: User cache: /Users/colin/.sonar/cache