I have been commenting on another thread related to this issue: https://techcommunity.microsoft.com/t5/azure-virtual-desktop-feedback/you-ve-broken-the-ability-to-connect-to-an-rd-gateway/idc-p/3071732#M560
I did install the current 10.7.4 release and I still have the same issue and error message. I can confirm I can connect to the Remote Desktops and the same gateway using the Windows Remote Desktop client. The issue is only occurring with remote desktop connections using a Load Balancing gateway. I can connect to other remote desktops with non load balancing gateway without issue. I am connecting to client's remote environments so I cannot setup a test user and login but I can work with a MS Engineer and have them shadow me while connect.