You can't do it with a workspace because all engines are in use, but you might be able to do it with an Automation.
Schedule it for a time when you would not expect to see any workspace running, like 9pm or 5am.
In the automation you can make an HTTP request to FME Server's own rest API to get the number of jobs queued or running. https://docs.safe.com/fme/html/FME_REST/apidoc/v3/index.html#!/transformations/listRunning_get_28
Then add a Filter looking for something like \\"totalCount\\":0 in the http response_body, if it fails that filter, then something is running when it normally wouldn't be, and you can send an email from the Automation.
You can't do it with a workspace because all engines are in use, but you might be able to do it with an Automation.
Schedule it for a time when you would not expect to see any workspace running, like 9pm or 5am.
In the automation you can make an HTTP request to FME Server's own rest API to get the number of jobs queued or running. https://docs.safe.com/fme/html/FME_REST/apidoc/v3/index.html#!/transformations/listRunning_get_28
Then add a Filter looking for something like \\"totalCount\\":0 in the http response_body, if it fails that filter, then something is running when it normally wouldn't be, and you can send an email from the Automation.
Not sure if that would work since the Log and Filter actions are workspaces too.