ColdFusion fails to include custom HTTP response header set in IIS 8.5

(this is a cross-posting of a question I asked on Server Fault: ColdFusion fails to include custom HTTP response header set in IIS 8.5 - Server Fault)

I have a Windows 2012 R2 server running IIS 8.5 and ColdFusion 11. Under a specific directory ("mydirectory") I added an HTTP Response Header (Name: X-ResponseHeader, Value: Test). The resulting web.config section looks like this:

<?xml version="1.0" encoding="UTF-8"?><configuration>    <system.webServer>        <httpProtocol>            <customHeaders>                <add name="X-ResponseHeader" value="Test" />            </customHeaders>        </httpProtocol>    </system.webServer></configuration>

I created several test files:

• test.cfm
• test.html
• test.png

I used curl -I to request the files and examine the response headers:

• test.cfm does not include the response header
• test.html includes X-ResponseHeader: Test
• test.png includes X-ResponseHeader: Test

Additionally, a request for a non-existent .cfm file does not include the header, but a request for a non-existent .png file does. Therefore I suspect that the ColdFusion handler is ignoring or removing the header, but I am not sure why.

Also of note: if I set a custom header at the site level in IIS, rather than at the folder level, the custom header is included in all cases.