When product has APIcast in hosted mode, saving any proxy setting in the new Integration > Settings page of APIAP is a no-op.

Dev note
The root cause seems to be a safety mechanism probably introduced to protect Saas: https://github.com/3scale/porta/blob/master/app/lib/api_integration/settings_result.rb#L24

In the same PR, we also limited the proxy params only to endpoint and sandbox_endpoint https://github.com/3scale/porta/blob/eaf4b508de85199ae0caaa268904880af5bdf445/app/controllers/api/services_controller.rb#L103.

To be fair though, before that PR, maybe not even the endpoints were being handled by Api::ServicesController, so updating proxy params is probably a bug in that Settings page since introduced.