Webclient not working

Hi, 

We have a host pool running and I just noticed we can't start sessions using the web client

https://rdweb.wvd.microsoft.com/webclient

Login is successful and the HP is listed in the subscriptions but when you click it to start a session, nothing happens, no error, just nothing. I tried it with several different accounts on multiple browsers on both Windows and Mac (Chrome, Edge and FF). All works fine with the same accounts using Windows RD Client (1.2.675).

We have Mac users that are on High Sierra, where the Mac Client doesn't work so I wanna make sure they can connect using the WebClient.