wechat sending image file error

hi all,

i have issue with my fortigate 100E, i'm using ip policy ip4 and enabled security profiles antivirus, webfilter, and etc sometimes its make wechat program can't send picture image (only with wechat, other app like whatsapp no issue). if i disabled those fitures can send again.

please kindly advice what need to do..thank you in advance.

Hans