I think this is related to how channels are cached.

You can reproduce this by calling AHC with proxy server enabled and then calling AHC without the proxy server enabled. (Important that this needs to be executed sequentially NOT in parallel)

Result is that the second AHC call grabs the cached Proxy server channel which is not correct. Expected result is that the second AHC call should not use the Proxy server but should just go to the destination server.

Workaround is to disable connection pooling with .setAllowPoolingConnection(false) which explains this behavior.

Tried with 1.7.x versions.