Q:

JMeter can't catch cookies with user defined variables

I got a HTTP Request Defaults, HTTP Cookie Manager and HTTP Request. Everything works with this group, the cookie is caught successfully. 

However, when I add a User Defined Variables to parameterize the url host and port, the request fails, and it shows [no cookies].
The detail of User Defined Variables: name = host, value = ${__P(host,xxxxxxx)}; name = port, value = ${__P(port,xxxxxxx)}
The detail of HTTP Cookie Manager: Cookie Policy = netscape

A:

Not sure why, but add 'CookieManager.check.cookies=false' to 'user.properties' could fix the problem

