WiFi login issue - authenticating through a proxy

The issue we have is our Dtek50's are built using Android for Work on a BES UEM. Our in-house corporate WiFi requires a login to authenticate. After the Android System WebView and Android Security Update last week the phones cannot authenticate because the cannot get through the proxy to reach the webpage to allow them to authenticate onto the internet.

Has anybody else got this issue? I have tried to white-list the services in the BES and the unblock the pages using a proxy bypass configuration in the Chrome set up. Nothing is working as yet. If the WiFi just has a password then everything is ok - it is just with WiFi with a splash login screen that appears to fail.