ionic app cannot connect cors enabled server with $http
cordova-plugin-whitelist seems to be "mandatory" at present.
install it :
cordova plugin add cordova-plugin-whitelist
configure config.xml
You can keep your current setup with * or change for more restrictive rules
add a html policy on index.html, you shall add a Policy also. To authorise everything, here it is :
<meta http-equiv="Content-Security-Policy" content="default-src *;
style-src 'self' 'unsafe-inline'; script-src 'self' 'unsafe-inline'
'unsafe-eval'"