Please can someone verify if this is a bug in modsecurity or just my installation.

SecResponseBodyAccess On
SecResponseBodyMimeType text/plain text/html text/xml
SecResponseBodyLimit 524288
SecResponseBodyLimitAction ProcessPartial

SecAction "phase:3,log,pass,msg:'phase3isWorking',id:'1500000'"


Request a resource that returns content type text/html and the above rule does not run.
Request a resource that returns content type image/png image/jpeg etc and rule runs ok.

Thanks
Ben