So I believe I have the same issue but it doesn't involve writable disks. Mine revolves around users with more then 3 or 4 app stacks assigned by App Volumes. If no App Volumes are assigned USB redirection works as desired. I believe the length of time it takes to attach these volumes is exceeding 60 seconds. Will crack my master and change the value to 200. This makes a lot of sense to me. Will report back with the verdict in my case.