Jean-Pierre, if you can, trying viewing the Chrome developer tools (or other browsers have similar tools) and look at the browser's console while you are waiting at the "Configuration en cours ..." loading screen:
I'm curious if you see:
Using SAW service for edit
Waiting for an app provision response
... or if your sequence stops earlier and/or if you see any errors mentioned in the browser console.
The states mentioned on the app loading screen while opening an app are:
"Setting up..." / "Configuration en cours..."
"Processing..." / "Traitement en cours..."
"Optimizing..." / "Optimisation en cours..."
"Opening..." / "Ouverture en cours..."
"Complete" / "Opération terminée"
If your apps always fail at the first step... I'm curious if you are able to open any of the demo apps on the site successfully, for example, the "Happiness" app:
This could help determine if the issue is with your particular app or something more general with your browser/network setup.
Perhaps you are having issues with websockets from your computer/network? To help rule out an issue with websocket communication you could check the results you get from some a websocket test page, for example:
For Qlik Sense and qlikcloud.com to operate correctly requires stable websocket connectivity.