To prevent unautorized network access, Copay and Bitpay Wallet v5.3.0 and above use the following Content Security Policy (CSP)
This restrict network connections to the listed hosts only. As a consecuence, accessing self-hosted Bitcore Wallet Service (BWS) hosts will not be allowed. If you are using a self-hosted BWS you need to build the app yourself from source and modify that above line (at app-template/index-template.html) to match your host.