Unfortunately, cache_dirs did not help, but thanks for the suggestion. You can close the app on the fire stick, but that did not allow the drives to spin down either. Over and over again in the log I get this message. I have all DLNA related services disabled. It's been a while, but I moved off of Plex because of a very similar reason. Plex kept writing to the log file which kept the hard drive from spinning down. Any thoughts? I am running a test now to confirm whether the fire stick had anything to do with it, it has been physically disconnected from the TV and from power. I'll post here in a few whether that allows the drives to spin down or not.
[2020-09-30 17:05:44.610 -05:00] [ERR] [16] Emby.Dlna.Main.DlnaEntryPoint: Error sending socket message from "10.253.0.1" to "239.255.255.250:1900"
System.Net.Sockets.SocketException (0xFFFFFFFF): Bad value for ai_flags
at System.Net.Sockets.Socket.DoBeginSendTo(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags, EndPoint endPointSnapshot, SocketAddress socketAddress, OverlappedAsyncResult asyncResult)
at System.Net.Sockets.Socket.BeginSendTo(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags, EndPoint remoteEP, AsyncCallback callback, Object state)
at Emby.Server.Implementations.Net.UdpSocket.SendToAsync(Byte[] buffer, Int32 offset, Int32 size, IPEndPoint endPoint, CancellationToken cancellationToken)
at Rssdp.Infrastructure.SsdpCommunicationsServer.SendFromSocket(ISocket socket, Byte[] messageData, IPEndPoint destination, CancellationToken cancellationToken)