Job priority doesn’t always work

Can anyone tell me why Muster’s job priority doesn’t always seem to work? All other things being equal, it seems like this sometimes just gets ignored, which is obviously a pretty large problem in a production situation where you have different projects competing for valuable render time and you have strict guidelines regarding who takes priority. I have seen this a few times at my place of work now, where a job with a lower setting will start to get picked up by render nodes even while there is clearly another, unfinished job with a higher priority still rendering and with unstarted chunks. Since we rarely use pools here this is not a pool issue, either — this is happening with jobs that have been submitted to the entire farm pool. I am not the render farm admin here and have limited experience with running Muster, but I have run many farms with Smedge and am wondering if there is some overriding priority setting that comes from the submitting machine or user? If it’s not that, then what is the problem here? Thanks.