OK, we just went through using System policy, and IP assumptions on NAT traffic with 6.5.
It all worked as expected. So, wondering what special settings you may have that give you a different experience.
If you can open up a support ticket at
http://support.qbik.com, and we can get some more information off you (e.g. WinGate registry etc) to progress this.
Regards
Adrien