Hi @Dennis_K, our team has been testing but have not been able to reproduce the issue.
I still continuing to investigate, I did find some info on the javascript error that the client is receiving:
Here is some additional info: windows 10 - Getting Unchecked runtime.lastError on chrome whenever moving the mouse - Super User
It might be this connection getting closed is what is breaking the connection in the editor.
It could also be some firewall is the client behind a company/organization firewall ?
It may be helpful to check to see if your local browser cache is disabled in the browser that is used with the designer.
This will help to force a re-download of latest page changes when those are made, as opposed to pulling from local browser cache.
See here as an example step by step to disable browser cache in Chrome: https://www.technipages.com/google-chrome-how-to-completely-disable-cache
As a last resort, it may help to completely uninstall chrome and then re-install. Thanks in advance.