Jenkins is not showing any feedback and doesn't either update its matrix-based security, for the moment I cannot modify any user or group in this matrix, the only feedback I get comes from the log which is the following:
Jan 09, 2015 7:35:17 PM org.eclipse.jetty.util.log.JavaUtilLog warn
WARNING: HttpParser Full for SCEP@57dd0c13
-{AsyncHttpConnection@7143e075,g=HttpGenerator
{s=0,h=-1,b=-1,c=-1},p=HttpParser
{s=-1,l=7266,c=21549},r=0}
Thanks a lot for your attention
More of a support request than a bug report, therefore closing as Not A Defect. The users mailing list or #jenkins may be able to help here.