Here's how to Cancel a Job that is stuck pending for an environment. This is needed so that further jobs against that environment will continue to run, and won't be blocked by a job emdash thinks is already running against it.
First, find the ID of the job that is 'stuck'. You can do this by hovering over the Job Details icon and looking at the URL that the link would take you to.
For example, in the following URL the Job ID is 86
At the moment, setting the job status to cancelled needs SQL Management Studio. Open SQL Management Studio so you can run some SQL against the emdash Database.
Update deploymentJob set DeploymentJobStatusId = 4 where id = 86 -- (where 86 is the ID above and 4 is the code for ‘Failed’)
Now if you go back to emdash and refresh the page, the status should be 'Failed'.