Allowing PT Scan for URLs in Fortinet

i have a set of public urls which are required to be VA/PT scanned by an external agency.. the problem is when the traffic gets initiated from the PT server i can see traffic getting blocked in fortigate via an IPS profile mapped in the access policy..i then added the IP of PT server in exemption list post which there were no IPS deny logs ..however, there are logs with 'blank" action and a message of server-rst... there is no issue with application at the same time as it is working fine as checked from a diff system.. i am suspecting a setting in fortigate which is seeing this as an attack but cant figure out what it is..

anyone faced a similar issue ? any help is appreciated.

thanks