This defect is duplicate of defect CSCur95616 and it has been verified fixed in AVC version 1.1.0.29 (which is the current AVC version).
The findings when the issue still persist is that in access logs of WSA, seeing below logs and not been identify by AVC engine as application signature:
1416596952.323 3011 10.176.140.154 TCP_CLIENT_REFRESH_MISS_SSL/200 3555 POST https://us-mg5.mail.yahoo.com:443/ws/v3/mailboxes/@.id==NzMxMjE1MDkwIDEyMjEzMCAxMjIxIHphY2ttYW4yMDAyQHlhaG9vLmNvbQ/messages?&appid=YahooMailNeo&wssid=5wWBAGpK6j2&ts=1416596949313&ymreqid=cd22af7f-4bf9-210a-0179-a70001010000 "CARLSON\zbrantley@CarlsonAD" DIRECT/216.115.98.107 text/plain ALLOW_WBRS_11-CarlsonStandard-CarlsonStandard-NONE-DefaultGroup-NONE-NONE <IW_mail,8.3,-,"-",-,-,-,1,"-",-,-,-,"-",-,-,"-","-",0,-,IW_mail,-,"-","-","Yahoo Mail","Webmail","-","-",9.45,0,-,"-","-"> -
However in the latest version of AVC, this issue has been fixed.
Hope this helps