that sounds more like a bug that should be looked into and fixed, rather than something that should just be ignored and a button on the front page added as a workaround (presuming that would even fix it)
youre going to need to enable debug logging, then upload the logs from a time period when it happens so that they can take a look and see if theres something in those logs that will help to fix it.
you may, in the mean time, check the system > tasks page to see if the refresh monitored downloads task is stuck, and kick it off manually to see if that resolves it or not.
alternatively you could go to wanted > manual import, add/select your downloads path, then do an interactive (or an automatic) import to do the moves for you - you will need to clean up the completed download jobs in the download client though (typically you just cancel the job and it deletes everything).