The GUI and CLI (powershell) disagree regarding where the slot index begins. The GUI counts beginning 1, 2, 3... while the CLI begins 0, 1, 2....
At best this is a confusing timesink for users who frequently switch between CLI and GUI. At worst this could lead to loss of customer data should a customer erase a tape in slot 7 when the tape they actually wanted was in slot 6.