Unfortunately @ionic/cli-plugin-proxy doesn’t work either. In general i use ionic serve too, but i’m having a rought time with ionic serve and the ion refresher (Ionic 4 - Ion refresher bug) so i wanted to test the app on ionic run… what a pitty.
Even if i use ionic cordova run browser proxy get all messed up. Instead of http proxy-address/address-you-want, the app is trying of http localhost:8000/proxy-address/address-you-want