In JobQueueInfo in the field Job server state, after pressing F5 to get the actual server states, the following error message appears for a Job Server; (Invalid URI: The format of the URI could not be determined).
From the same machine you are able to see the Job Service Status of the Job Servers in a web browser without issue.
You can resolve this by opening the Object Browser:
In navigation view, go to the JobServer folder, click on the job server with the error, in events click GetConfig>Generate
Once this process completed, resart the JobQueueInfo frontend and refresh the Job Server States.