JBOSS Logging per deployment issue - eclipse

Question

we've an application, running in JBOSS EAP 6.4, generating a lot of logs. So we decided to give the application its own log, rotating each hour.
The application uses SFL4J, which is compatible with JBOSS Logging.
As we can't change parameters on JBOSS config we decided to use the logging per deployment feature and added, following the developers manual, a file logging.properties in the classpath, with the File Handler set up as below
handler.FILE=org.jboss.logmanager.handlers.PeriodicRotatingFileHandler
handler.FILE.level=ALL
handler.FILE.formatter=PATTERN
handler.FILE.properties=append,autoFlush,enabled,suffix,fileName
handler.FILE.constructorProperties=fileName,append
handler.FILE.append=true
handler.FILE.autoFlush=true
handler.FILE.enabled=true
handler.FILE.suffix=.yyyy-MM-dd-HH
handler.FILE.fileName=${jboss.server.log.dir}\\pfl.log
While in DEV station everything works as expected (JBOSS Developer Studio 7.1.1 with JBOSS EAP 6.1), in production and test JBOSS generates correctly the pfl.log file and the hourly backups, BUT the pfl.log is never made empty. So it's growing indefinitely (and so the hourly files). Also we noted that the same behavior happens using dayly rotating logs
handler.FILE.suffix=.yyyy-MM-dd
This is getting us crazy.. How can we solve this ? Where can be the problem ? Did we make any config mistakes ?