Error messages in the Power BI Report Server are one of the areas we know we need some specificity. Sorry for the vague message, but I can help you get something more useful. Can you open the developer tools in your console (f12 by default) perform the description edit and see if you get an error under the network tab. Below is an example of what to look for in edge.
Additionally we can take a look at the log files from the reportserver under C:\Program Files\Microsoft Power BI Report Server\PBIRS\LogFiles\ look for the latest ReportingServicesService_*.log.
Once we have this we can take a look at what possible issues could be.
You can ignore the above request for logs I was able to reproduce this issue locally. It's a regression of functionality and will require a fix to the server. It has been added to our backlog as a high priority bug.