Image files sending to sandboxing from CAS

Dears,

I noticed that CAS isn’t sending image files “ipeg, ipg, png” to MAA for sandboxing, even with configuring sandbox threashold with value 0, which means sending all files to sandboxing.

Also, I tried manual image file scanning and I got the result expect sandboxing = false.

ICAP/1.0 204 No modifications needed
X-Apparent-Data-Types: JPG
X-ICAP-Metadata: { “expect_sandbox”: false }
Service: CAS 2.2.1.1(207429)
Service-ID: avscanner
ISTag: “5A9552CC”
Encapsulated: null-body=0
Date: Tue, 27 Feb 2018 12:53:45 GMT

I tried adding the extension on CAS sandboxing settings with no added value.

any Ideas why the image files aren’t sent to sandboxing.

Thanks in advance,