Symptoms

It's impossible to launch published Desktop using HTML5 client, it gets stuck in Connecting... state forever:

Published apps can be started just fine.

Cause

Parallels Engineering is aware of the issue and is working on the resolution.

Resolution

Please consider using Parallels Client for the client OS instead of HTML5.
If you need to keep using HTML5 client, here is a workaround:

1. Please go to RAS Console → Publishing;
2. Locate the published desktop and go to the Desktop tab;
3. Change screen resolution from Full screen to any other option: